SumatraPDF Portable Settings Not Saving: How to Fix It

When SumatraPDF portable settings are not saving, the usual symptom is straightforward: you change a theme, view option, history entry, favorites list, or document state, close the reader, and discover that the change has disappeared when you reopen it. In portable mode, SumatraPDF is expected to keep its settings file beside SumatraPDF.exe rather than relying on the installed application's normal user-profile location.

The most likely causes are a folder that cannot be written to, a read-only USB drive, security software removing or blocking the settings file, confusion between installed and portable copies, or a damaged or incorrectly named SumatraPDF-settings.txt file. The steps below isolate those possibilities without requiring registry editing, developer tools, or an immediate reinstall.

1. Confirm the Symptom With One Simple Test

Before changing permissions or deleting files, confirm that the problem is persistence rather than a document-specific feature. Use one ordinary local PDF and one easily visible preference. This avoids confusing settings storage with rendering, printing, file-format support, or restrictions inside a particular document.

1.1 Run a controlled preference test

1. Close every open SumatraPDF window.
2. Open the portable folder containing SumatraPDF.exe.
3. Launch SumatraPDF.exe directly from that folder.
4. Open a normal PDF stored in your Documents or Downloads folder.
5. Change a visible setting, such as the application theme, page layout, or remembered window size.
6. Close SumatraPDF normally.
7. Wait a few seconds, then launch the same SumatraPDF.exe again.

If the preference remains changed, portable persistence is working. Stop changing folder permissions or resetting files. The original symptom may instead concern one document, one shortcut, or a different copy of the program.

If the preference resets, inspect the folder beside SumatraPDF.exe. A portable setup should have a file named SumatraPDF-settings.txt there after SumatraPDF has run and saved its state. Note whether the file exists and whether its modified date changes when you close the application.

1.2 Interpret the result

• No settings file appears: the executable folder may not be writable, or you may not be running the copy you think you are.
• The file exists but its date never changes: it may be read-only, blocked, or inaccessible to the current Windows account.
• The date changes but preferences still reset: another process may be replacing the file, or multiple copies may be using different settings files.
• Only one document loses its position: the problem may involve history settings, document identity, or a document opened from a temporary location.

2. Check the SumatraPDF File and Launch Path Directly

File associations and shortcuts can make portable troubleshooting confusing. Double-clicking a PDF does not guarantee that Windows launches the SumatraPDF.exe in the portable folder you are inspecting. Windows may open an installed copy, an older portable copy, or a copy on another drive.

2.1 Verify the executable you are actually running

Close SumatraPDF, browse to the intended portable folder, and double-click SumatraPDF.exe itself. Perform the preference test again. Do not begin with a PDF file, taskbar icon, Start menu result, or old desktop shortcut.

If direct launching fixes the problem, the application was capable of saving settings and the shortcut or file association was pointing elsewhere. Replace the old shortcut with one created from the correct executable. If desired, update the Windows default app for PDF files only after confirming the correct copy.

Success means that direct launches and subsequent document launches use the same preferences. Once that happens, stop editing settings files. The remaining job is simply to remove or update misleading shortcuts and associations.

2.2 Find multiple portable copies

Search likely locations for additional files named SumatraPDF.exe. Common places include Downloads, Desktop, a USB drive, an extracted ZIP folder, a synchronization folder, and an older utilities directory. Multiple copies are not inherently harmful, but each portable folder can maintain its own SumatraPDF-settings.txt.

Check the path stored in desktop shortcuts by opening the shortcut's properties and reading the Target field. Unpin an outdated taskbar shortcut before pinning the confirmed executable again, because pinned items can continue launching an old path.

If one copy remembers changes and another does not, no global SumatraPDF failure exists. Keep the desired copy, clearly rename its parent folder, and remove obsolete shortcuts. You can archive older copies rather than deleting them immediately.

2.3 Consider a folder moved between drives

Moving a portable folder from one drive to another can expose different permissions, drive policies, or shortcut targets. A shortcut may still reference the former drive letter, while a removable drive can receive a different letter on another computer. Settings may also appear missing if only SumatraPDF.exe was copied and SumatraPDF-settings.txt was left behind.

For a complete move, close SumatraPDF and copy the entire portable folder, including SumatraPDF-settings.txt. Then launch the executable directly from its new location. Success means the existing preferences appear and the settings file's modified time updates after a controlled change.

3. Check Windows and Storage Conditions That Block Portable Saving

Portable mode depends on write access to the executable folder. This is the key difference from an installed application that stores user settings under the Windows profile. A portable executable can run successfully from a location even when it cannot create or update files there.

3.1 Avoid Program Files for a portable copy

Program Files and Program Files (x86) are protected Windows locations intended for installed software. Standard user processes commonly lack permission to modify application files there. As a result, SumatraPDF.exe may open documents normally while failing to update a settings file beside itself.

Move the entire portable folder to a user-writable location such as a dedicated folder under Documents. For example, create a folder named PortableApps under Documents, place the complete SumatraPDF folder inside it, and launch the executable directly.

Do not use permanent administrator privileges as the preferred fix. Running as administrator can mask a poor portable location and create inconsistent behavior between elevated and normal launches. Success is being able to save settings during an ordinary, non-administrator session.

3.2 Test read-only USB drives and removable media

A USB drive can become effectively read-only because of a physical lock, file-system errors, device policy, security software, or permissions inherited from another system. Some managed computers also prohibit writing to removable media.

In File Explorer, try creating a small text file in the same folder as SumatraPDF.exe. Delete the test file afterward. If Windows refuses to create it, SumatraPDF will not be able to maintain portable settings there either.

Copy the complete folder to a writable local folder and test again. If settings save locally, SumatraPDF is working and the removable drive or its policy is the cause. Stop resetting SumatraPDF and address the drive's write access, or use the local copy.

3.3 Inspect file and folder attributes

Right-click SumatraPDF-settings.txt, choose Properties, and check whether the file itself is marked read-only. Clear that attribute if present, apply the change, and repeat the preference test. Also confirm that your Windows account can modify files in the parent folder.

The read-only box displayed for a folder can behave differently from the read-only attribute on an individual file, so the practical create-file test is more useful than relying only on the folder's Properties dialog. If you can create, edit, save, and delete a text file in that exact directory, basic write access is available.

3.4 Check antivirus and cleanup activity

Antivirus, endpoint protection, ransomware protection, synchronization tools, and automated cleanup utilities can block, quarantine, restore, or delete files in application folders. Review Windows Security protection history and any third-party security logs for events involving SumatraPDF.exe or SumatraPDF-settings.txt.

Do not disable protection broadly. If a trusted, official SumatraPDF copy is being blocked, use the security product's documented allow-list process or choose an ordinary user-writable folder that is not subject to aggressive cleanup. On managed work computers, ask the administrator rather than changing organizational security controls.

Success means the settings file remains present and receives a new modified timestamp after SumatraPDF closes. If it disappears later, note the time and compare it with cleanup, synchronization, or security logs.

3.5 Separate persistence from document and rendering problems

A damaged source document, unsupported content, missing external component, printer driver problem, or rendering issue can affect how one file opens or prints. Those factors normally do not prevent a portable application from writing its general settings file. Likewise, DRM and document restrictions should not be bypassed and are not a reason to alter portable storage.

If themes and window preferences save but one document does not reopen at the expected page, test a simple local PDF. Documents opened from email attachments, browser caches, archives, or temporary directories may receive changing paths or filenames. SumatraPDF may then treat the item as a different document.

Codecs, Ghostscript, printer drivers, and external conversion tools should be investigated only when the actual symptom involves a format, PostScript workflow, preview, conversion, or printing. Installing them is not a reasonable fix for a SumatraPDF-settings.txt file that cannot be updated.

4. Inspect or Reset SumatraPDF-settings.txt Safely

If the portable folder is writable and the correct executable is running, inspect the settings file without immediately destroying it. The file can contain preferences, history-related data, favorites, and other state that you may want to preserve.

4.1 Back up the current file

1. Close all SumatraPDF windows.
2. Open the folder containing the confirmed portable SumatraPDF.exe.
3. Copy SumatraPDF-settings.txt to a separate backup folder.
4. Name the backup clearly, such as SumatraPDF-settings-backup.txt.

Do not edit the live file while SumatraPDF is open. The application may write its in-memory state when closing and overwrite manual changes.

4.2 Check the filename and location

Confirm that the file is named exactly SumatraPDF-settings.txt. If Windows hides known file extensions, a file that appears correct might actually be named SumatraPDF-settings.txt.txt. Enable file-name extensions in File Explorer to verify it.

The file must be beside the portable SumatraPDF.exe being launched, not merely beside a shortcut or PDF. If several settings files exist, compare their folder paths and modified dates rather than assuming the newest-looking program icon is the active copy.

4.3 Reset only after making a backup

With SumatraPDF closed, rename the live settings file to SumatraPDF-settings.old.txt. Launch SumatraPDF directly. A fresh settings file should be created when the application saves state, provided the folder is writable.

Change one visible preference, close the application, and reopen it. If the change persists, the previous settings file was likely damaged, malformed, locked, or being restored from an unwanted copy. Keep the backup until you have confirmed that essential preferences and favorites are available.

If no new file appears, the old file's contents were probably not the primary cause. Restore it if needed and return to folder permissions, launch-path verification, security controls, or the clean local test.

5. Run a Clean Temporary Test Before Reinstalling

A clean portable test is the fastest way to separate an application-wide problem from a location-specific problem. It also avoids modifying the working folder repeatedly.

5.1 Create a writable local test folder

1. Download SumatraPDF only from its official website or use a trusted portable package you already verified.
2. Create a new folder under Documents, such as SumatraPDF-Test.
3. Place a clean portable SumatraPDF.exe in that folder.
4. Do not copy the old SumatraPDF-settings.txt into the test folder.
5. Launch the test executable directly.
6. Change one visible preference and open one ordinary local PDF.
7. Close the program and check for a new SumatraPDF-settings.txt.
8. Reopen the same executable and verify the preference.

If the test copy saves correctly, reinstalling Windows components, adding codecs, changing printer drivers, or modifying documents is unnecessary. The original portable folder, old settings file, shortcut, removable drive, or security rule is responsible.

If the clean copy also fails in a writable Documents folder, verify that the test file can be created manually, inspect security logs, and make sure every SumatraPDF process has closed in Task Manager. A managed Windows policy may be preventing application writes.

5.2 Decide what to keep

When the clean test succeeds, you can use the new folder as the permanent portable location. Close SumatraPDF before copying any backed-up settings file into it. If restoring the old file immediately recreates the problem, return to the newly generated file and reapply preferences manually.

Success looks like three consecutive outcomes: the settings file exists beside the intended executable, its modified time changes after a setting change, and the preference survives a full close and relaunch. Once all three are true, stop troubleshooting.

6. Quick Fix Checklist

• Launch SumatraPDF.exe directly instead of using an old shortcut or file association.
• Confirm SumatraPDF-settings.txt is beside the executable you actually launched.
• Move portable SumatraPDF out of Program Files and into a writable user folder.
• Test whether you can create and delete a text file in the portable folder.
• Copy the complete portable folder when moving between drives.
• Check for multiple SumatraPDF.exe copies with separate settings files.
• Remove the read-only attribute from the settings file when applicable.
• Review antivirus, ransomware protection, synchronization, and cleanup logs.
• Back up and rename the settings file before allowing a fresh one to be created.
• Run a clean test under Documents before reinstalling or deleting anything else.

7. Frequently Asked Questions

7.1 Where should portable SumatraPDF store its settings?

Portable SumatraPDF should keep SumatraPDF-settings.txt in the same folder as SumatraPDF.exe. If you are inspecting a file under a Windows user-profile application-data directory, you may be looking at an installed copy rather than the intended portable instance.

7.2 Why does SumatraPDF open files but fail to save preferences?

Windows can permit an executable to run and read documents without allowing it to create or modify files in its own folder. This commonly occurs in Program Files, on read-only removable media, or in directories controlled by security policy.

7.3 Will reinstalling SumatraPDF fix portable settings?

Not necessarily. Replacing the executable does not correct an unwritable folder, stale shortcut, read-only drive, or security rule. Run a clean portable copy in a writable local folder first. Reinstall only if that controlled test indicates the executable itself is incomplete or damaged.

7.4 Why is document history missing after moving the folder?

The settings file may not have been copied with the executable, or a shortcut may still launch the copy on the previous drive. Move the entire closed portable folder, then launch SumatraPDF.exe directly from the destination and verify the settings file there.

7.5 Can file associations cause settings to appear inconsistent?

Yes. A PDF file association can launch a different installed or portable copy. Each copy may read and write settings in a different location. Directly launching the desired executable is the simplest way to prove which copy owns the preferences you are testing.

7.6 Should I delete SumatraPDF-settings.txt?

Rename and back it up instead of deleting it immediately. A fresh file can reveal whether the original is damaged, while the backup preserves preferences, favorites, and other useful state. If a new file does not solve the problem, focus on write access and launch paths.