How we store settings

Where we store settings #

Persisted data is stored in SumatraPDF-settings.txt file.

In portable version the file is stored in the same directory as SumatraPDF executable. In non-portable version, it’s in %LOCALAPPDATA%\SumatraPDF directory.

Starting with version 1.6 we also persist thumbnails for “Frequently read” list. They are stored in subdirectory sumatrapdfcache as .png files.

Override the directory with -appdata <path> on the command line — see Installation.

See https://www.sumatrapdfreader.org/settings/settings for information about all the settings.

How settings apply #

Not every setting works the same way. Understanding the three layers avoids “I changed it but nothing happened” confusion.

1. Global defaults (first open) #

Settings like DefaultDisplayMode and DefaultZoom in advanced settings apply when you open a document for the first time — when there is no saved state for that file yet.

The Settings → Options dialog (“remember these settings for each document”) writes global defaults into the same settings file. They do not retroactively change files you have already opened.

2. Per-document state (reopen) #

When RememberStatePerDocument = true (default), SumatraPDF saves display settings per file in the FileStates section: zoom, scroll position, view mode, sidebar width, tab color, etc.

The next time you open that file, saved state wins over global defaults. This is why changing “default two-page view” does not affect a PDF you have opened before — see FAQ.

To reset one file: delete its [[FileStates]] block from the settings file, or delete the entire settings file to reset everything.

3. Restart-required settings #

Some settings apply only after restarting SumatraPDF:

UseTabs — tabbed vs separate windows for new windows
Others noted in advanced settings (e.g. some UI layout options)

ReuseInstance and most color/theme changes take effect immediately or on the next file open.

Session restore #

Setting	Effect
`RestoreSession = true`	On startup, reopen tabs and window layout from `SessionData`
`RememberOpenedFiles = true`	Track history for Home / `#` command palette
`LazyLoading = true`	When restoring session, load tab content only when the tab is selected

-for-testing skips restore and does not save settings.

What is not in the settings file #

Unsaved annotations — kept in memory until you save or discard; see Editing annotations
Installer / restrict policy — sumatrapdfrestrict.ini beside the executable; see Configure for restricted use

Reset to defaults #

Delete SumatraPDF-settings.txt. SumatraPDF recreates it on next launch with factory defaults.