SumatraPDF Zoom or View Mode Not Remembered: How to Fix It

If SumatraPDF keeps reopening a document at the wrong zoom level or returns to an unwanted layout, the problem is usually not the PDF itself. The most common causes are a saved per-document state overriding your global defaults, disabled document-state memory, an incorrect value in SumatraPDF-settings.txt, or Windows opening a different installed or portable copy. The steps below focus specifically on zoom and display-mode persistence, including Fit Width, Fit Page, single page, facing, book view, and continuous layouts. They do not treat last-page restoration as the only symptom.

1. Confirm the Symptom With a Simple Document Test

Start by determining whether the problem affects one document, every previously opened document, or all documents. This distinction matters because SumatraPDF can store both global defaults and per-document settings.

1.1 Test a PDF That SumatraPDF Has Never Opened

Use a simple, unrestricted PDF that you have never opened in SumatraPDF. If necessary, create a basic PDF from a text document or download a straightforward public PDF from a trusted source. Avoid testing first with an eBook, comic archive, CHM file, scanned document, or unusual PDF because format-specific behavior can complicate the result.

1. Close every SumatraPDF window.
2. Open the new PDF directly in the copy of SumatraPDF you intend to use.
3. Select a recognizable zoom setting, such as Fit Width.
4. Select a display mode, such as Single Page Continuous or Facing.
5. Close SumatraPDF normally.
6. Reopen the same file using the same method.

Success means the document returns with the selected zoom and display mode. If it does, SumatraPDF can write settings, and the original document probably has an old or conflicting entry in its saved file state. Stop changing global settings and reset only that document as described later.

If the new PDF also loses its settings, repeat the experiment with another never-opened PDF. When both fail, investigate the global defaults, RememberStatePerDocument, the active settings file, and whether Windows is launching another SumatraPDF executable.

1.2 Separate Zoom Problems From Display-Mode Problems

Zoom and display mode are related but separate settings. Fit Width, Fit Page, Actual Size, and percentage values control magnification. Single page, continuous, facing, and book view control page arrangement and scrolling behavior.

Record exactly what changes after reopening. For example, Fit Width might persist while Facing changes to Single Page Continuous. That result points toward a display-mode value rather than a general inability to save settings. Conversely, if both settings and other preferences revert, the settings file may not be writable or you may be opening a different SumatraPDF copy.

2. Check the SumatraPDF Settings That Control Persistence

SumatraPDF uses global defaults for documents without saved state and can also maintain a state for each previously opened document. Understanding that priority resolves many cases where changing a default appears to have no effect.

2.1 Understand DefaultZoom and DefaultDisplayMode

DefaultZoom defines the initial zoom behavior used when no more specific saved state applies. DefaultDisplayMode defines the initial page arrangement. Depending on the supported document type and selected value, the display can use layouts such as single page, facing pages, book view, and continuous variants.

These are defaults, not necessarily commands that overwrite every document already listed in the saved file states. If you previously opened a PDF at 100 percent in single-page mode, that document's saved state can take priority over newly configured defaults.

To test a global default correctly, change it and then open a never-opened PDF. Success means the new PDF starts with the intended zoom and layout. At that point, stop editing the defaults. Existing documents need their individual state reset rather than repeated global changes.

2.2 Check RememberStatePerDocument

RememberStatePerDocument controls whether SumatraPDF remembers document-specific state. When enabled, SumatraPDF can restore settings associated with an individual file, including view-related information. When disabled, reopening a file is more likely to use global behavior instead of its previous per-document state.

Choose the behavior that matches your goal:

• Enable per-document memory if each PDF should reopen with its own last-used zoom and page arrangement.
• Disable it if you want documents to follow common defaults rather than retaining individual viewing states.
• Reset selected saved entries if you want per-document memory generally but one PDF has an incorrect state.

Do not repeatedly toggle this option while testing. Set the intended policy, close SumatraPDF normally, and reopen one test document. Success means its behavior now matches that policy.

2.3 Distinguish the Options Dialog From Advanced Settings

The standard Options dialog contains common user preferences, but it does not expose every advanced persistence value. Commands for opening advanced settings are intended for settings such as DefaultZoom, DefaultDisplayMode, and RememberStatePerDocument.

When advanced settings opens in a text editor, edit only the relevant value and preserve the surrounding structure. Use a value already recognized by the file's generated configuration or documented for your SumatraPDF release. Do not copy an entire settings file from an old forum post because available fields and formatting can change over time.

2.4 Confirm the View Mode Is Supported for the Document

Not every document format behaves like a fixed-page PDF. Reflowable eBooks may calculate pages according to window size, font settings, and content layout. Comic archives and image collections have different page characteristics. CHM and other formats can use format-specific navigation or rendering behavior.

First prove the desired mode works with an ordinary PDF. Then test the original format. If the mode is unavailable, disabled, or immediately replaced only for that format, the issue may be a format limitation rather than failed persistence.

3. Check Windows, File Launching, and External Factors

Windows can make a settings problem look inconsistent when different shortcuts or file associations launch different SumatraPDF copies. This is especially common when an installed release and a portable executable coexist.

3.1 Verify Which SumatraPDF Copy Opens the File

Test the application shortcut and Windows file association separately:

1. Close all SumatraPDF windows.
2. Launch SumatraPDF from the shortcut you normally trust.
3. Open the PDF from within SumatraPDF and test persistence.
4. Close the program.
5. Double-click the same PDF in File Explorer.
6. Compare the behavior and executable location.

If opening from inside SumatraPDF works but double-clicking does not, Windows may associate PDFs with another copy or another reader. Correct the default app association or remove obsolete shortcuts. Success means both launch methods open the same executable and produce the same zoom and view-mode behavior.

3.2 Understand Installed Versus Portable Settings

An installed copy normally keeps its user configuration in the Windows user profile, while a portable copy is designed to keep its configuration with the portable application when its folder is writable. As a result, the two copies can have different defaults and different per-document histories.

A portable copy placed in a protected directory may also be unable to update its local settings. Move it to a normal user-writable folder, such as a folder under Documents, before testing. Do not solve the problem by granting broad administrator access. The safer test is to use a location your Windows account already owns.

Success means the expected settings file receives an updated modification time after you close SumatraPDF normally. Once that happens, stop changing permissions or locations.

3.3 Check the Source Document and Its Location

A read-only PDF does not normally prevent SumatraPDF from storing viewer preferences because those preferences are maintained in SumatraPDF's own settings. However, moving, renaming, replacing, or opening a temporary copy of the document can make it appear to be a different file.

This can happen with email attachments, browser download previews, cloud-sync conflict copies, archive viewers, and document-management systems. Save the file to a stable local folder, open that exact copy, set the view, close SumatraPDF, and reopen the same path.

Password protection or document restrictions should not be bypassed. If a protected document opens normally, test whether basic viewing state persists without trying to alter the file or remove restrictions.

3.4 Consider Rendering Tools Only When the Format Requires Them

Codecs, Ghostscript, printer drivers, and external conversion tools are not typical causes of a PDF zoom preference being forgotten. Investigate them only when the original file depends on a particular renderer or when the symptom occurs during printing, conversion, or opening a specialized format rather than ordinary PDF viewing.

For example, if a converted or printed output always opens with different dimensions, test the original PDF independently. If a PostScript workflow relies on Ghostscript, isolate that conversion from SumatraPDF's saved viewing state. A successful ordinary-PDF test shows that reinstalling codecs or printer drivers is unlikely to fix persistence.

4. Inspect or Reset SumatraPDF-settings.txt Safely

The settings file is the central place to investigate when values revert, old document states override defaults, or an installed and portable copy behave differently. Treat it as user data and make a backup before editing.

4.1 Back Up and Inspect the Active File

1. Close every SumatraPDF window, including windows on other desktops.
2. Locate the settings file used by the active installed or portable copy.
3. Copy SumatraPDF-settings.txt to a safe backup location.
4. Open the original in a plain-text editor.
5. Find DefaultZoom, DefaultDisplayMode, and RememberStatePerDocument.
6. Check whether their values match your intended behavior.

Do not edit the file while SumatraPDF is running. The application can write its in-memory settings during shutdown and overwrite manual changes. After editing, save the file, start SumatraPDF, test once, and close it normally.

Success means the edited values remain in the file after shutdown and a never-opened PDF uses the intended defaults. If the text reverts immediately, confirm that you edited the active file and that its folder is writable.

4.2 Reset FileStates for One Document

The FileStates area contains entries associated with previously opened documents. An old entry can preserve an unwanted zoom or display mode and override the global defaults for that file.

With SumatraPDF fully closed and the settings file backed up, search the FileStates data for the exact path or filename of the affected document. Remove only the complete entry belonging to that document while preserving the surrounding list structure. If you are not comfortable identifying the full block, use the clean temporary test in the next section instead of guessing.

After saving, reopen that PDF. It should now behave like a document without stored state and use the current defaults. Set the desired zoom and display mode, close normally, and reopen it once. Success means the new state is remembered. Stop editing at that point.

4.3 Reset the Whole Settings File Only as a Last Resort

Renaming the entire settings file can clear preferences, history, window placement, and all per-document states. It is broader than necessary when only one PDF is affected.

If many settings are corrupted or nothing is being saved, close SumatraPDF and rename the file rather than deleting it. Start the application so it creates a fresh configuration, then test with a simple PDF. Keep the backup until you have confirmed that the clean configuration solves the problem.

5. Run a Clean Temporary Test Before Reinstalling

Reinstalling often leaves user settings untouched, so it may not resolve a persistence problem. A clean portable test is more informative because it separates the application from the existing configuration.

1. Download SumatraPDF only from its official website.
2. Place a portable copy in a new, writable folder.
3. Close every existing SumatraPDF process before launching it.
4. Open a never-opened, ordinary PDF from within the portable copy.
5. Select Fit Width and a distinctive supported display mode.
6. Close the portable copy normally and reopen the same file.

If the clean copy remembers the settings, the PDF and core application are working. The fault is likely in the original settings file, its write permissions, its per-document entry, or the shortcut and association used to launch the original installation.

If the clean copy fails only with one document, save that file under a stable local path and test another PDF. If every simple PDF fails in the clean copy, verify that the portable folder remains writable and that another running SumatraPDF instance did not handle the file-open request.

6. Quick Fix Checklist

• Test Fit Width and a display mode with a never-opened PDF.
• Decide whether you want global defaults or per-document memory.
• Check DefaultZoom and DefaultDisplayMode in advanced settings.
• Set RememberStatePerDocument according to the behavior you want.
• Reset only the affected document's FileStates entry when possible.
• Close SumatraPDF before manually editing its settings file.
• Confirm Windows shortcuts and PDF associations open the same executable.
• Keep portable SumatraPDF in a user-writable folder.
• Test a stable local copy instead of an attachment or temporary download.
• Use a clean portable test before reinstalling or deleting all preferences.

7. Frequently Asked Questions

7.1 Why Does Changing DefaultZoom Not Affect a PDF I Already Opened?

A saved per-document state can override DefaultZoom. Test the default with a never-opened PDF. If that file uses the new zoom, reset the old PDF's entry under FileStates instead of changing the global default again.

7.2 How Do I Make Every New PDF Open in Fit Width?

Set DefaultZoom to the supported Fit Width value in advanced settings, close SumatraPDF normally, and test a PDF it has never opened. Previously opened files may retain their own saved zoom when per-document state is enabled.

7.3 Why Is Facing or Book View Not Remembered?

First confirm that the document and layout support the selected mode. Then check DefaultDisplayMode and the document's saved state. Book view can also differ from ordinary facing mode because it treats the first page as a cover, so verify that you selected the intended layout.

7.4 Does RememberStatePerDocument Only Remember the Last Page?

No. Per-document state is relevant to more than page position. It can also affect viewing information such as zoom and display arrangement. That is why an old document entry can override global defaults even when last-page restoration is not the problem you are trying to solve.

7.5 Will Reinstalling SumatraPDF Fix the Problem?

Not necessarily. If the existing user settings remain after reinstallation, the same saved state or configuration problem can return. Run a clean portable test first. Reinstall only when the clean test suggests the application files themselves are damaged or the installed executable is not the one Windows is launching.

7.6 When Should I Stop Troubleshooting?

Stop once a never-opened PDF uses the desired defaults or the affected document reopens with its newly saved zoom and layout. Do not continue resetting settings, changing permissions, or reinstalling components after the intended behavior is confirmed. Additional changes can erase useful preferences without improving the result.