Changing default pdf viewer

[BloopX2]

Hi, I'm having trouble changing the default pdf viewer on my samsung s21 fe. I've tried going to "Settings > apps > choose default apps" but there's no pdf viewer option I've also tried doing "settings > apps > free adblocker browser (the browser I'm using) > defaults" but also no option for pdf viewer any ideas on how to change my default pdf viewer? 

BTW I don't wanna delete the app because I have all my passwords and work data on it

[AndrewL]

@BloopX2: Please can you try heading to Settings > Apps > Select the app you use to open your .pdf files by default > Set as default > Clear defaults > Clear. 

Now, tap the Home button > Swipe up from your Home screen > Samsung (folder) > My Files > Documents > Select a .pdf file > A series of app options should appear at the bottom of the screen > Tap the preferred app, then select 'Always'. Let me know if this helps. 

[BloopX2]

@AndrewL I can go to Settings > apps > my pdf viewer > defaults, but it only shows that I have it as my default browser. Even then, there's no "clear defaults" button

[TessM]

I see, @BloopX2 . In this case, I would suggest resetting your apps preferences from the phone Settings> Apps> Menu (3 dots top right)> Reset app preferences. Then try to open a .pdf document and select the app as your default.