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