Documentation : Setting Sumatra as default PDF reader

Before Win 10 you can just use Settings/Options menu at any time.

In Win 10 it’s more complicated. You can try the following methods.

  1. Right-click SumatraPDF.exe in c:\Program Files\SumatraPDF (or c:\Program Files (x86)\SumatraPDF ) and select Run as Administrator.
  2. Go to Settings > Options and click the button to set Sumatra as the default PDF viewer.
  3. Close the program.

If issue is still not solved:

  1. In file explorer, right-click any PDF > Open with > Choose another app .
  2. Check the _Always use this app to open .pdf files _ checkbox.
  3. Scroll down and click on the More apps ↓ link, then select SumatraPDF from the list and click on the OK button.
  4. If SumatraPDF is not in the list, scroll down and click on the Look for another app on this PC link.
  5. In the Open with… dialog navigate to c:\Program Files\SumatraPDF (or c:\Program Files (x86)\SumatraPDF ), select **SumatraPDF.exe ** and click on the Open button.
  6. The PDF should open with Sumatra, and all PDFs when subsequently double-clicked should open with Sumatra too.

If issue is still not solved:

  1. Open Settings app.
  2. Go to System > Default apps.
  3. Scroll down and click on the _Choose default apps _ by file type link.
  4. Set SumatraPDF a the default app for the .pdf file type.

Krzysztof Kowalczyk