1. Use the shortcut key [WIN+R] to open Run, enter "ms-settings:defaultapps" and press Enter;
2. In the setting window, you can see the relevant setting options under [Default Application];
3. Enter ".pdf" in the search box at the top and search for it. The default opening method is Microsoft Edge browser;
4. Click the [Change] button on the right side of the browser;
5. In the "From now on, how do you want to open the .pdf file?" window that pops up, select the application you want to open the .pdf file, and click OK.