If there are no other applications registered for a given extension, you can open the file in SumatraPDF simply by double-clicking the file in File Explorer.
If there is more than one application, you have to explicitly tell Windows 10+ to make SumatraPDF the default application.
Using File Explorer #
In File Explorer:
- find a
.pdffile (or any other supported file type) - right-click to open the context menu
- select
Open withand thenChoose another app
From the list, choose
SumatraPDF and check Always use this app to open .pdf files:
Using Default apps system settings #
This is based on the latest Windows 11 build at the time of writing.
Unfortunately the details differ between Windows updates.
Open the
Default apps section of the Settings app. For example, press the Windows logo key to open system-wide search, type default apps, and click the Default apps search result.
In Default apps, type
.pdf as the file extension:
Click the current default PDF application (
Microsoft Edge in this example) and select SumatraPDF:You can do that for other file formats.