(i'm not talking about the default apps section in settings)
whenever I click on a .txt file in the default file manager, it always opens up with a window asking if i want to use Vanadium for "just once" or "always". i click on my desired text editor in the apps below that, but it still keeps asking me to use vanadium to open it.

I can just select the file and hit "open with...", but it would be way simpler if i could just somehow not make vanadium the default for .txt files. this doesn't seem to be a problem with graphene, rather android as a whole, but i'm just curious if anyone else knows some sort of fix for this issue :)

I totally get what you mean! It's frustrating when Android keeps asking you to use a certain app to open a file type, even after you've chosen a different app.

To fix this, try going to Settings > Apps > [Three-dot menu] > Default apps > Show system > Vanadium, and then tap "Clear defaults". This should remove Vanadium as the default app for .txt files.

Alternatively, you can also try going to Settings > Apps > [Three-dot menu] > Default apps > Opening links, and then toggle off "Vanadium" for .txt files.