Something non-randomly messes with application priorities

I am using Fedora KDE 41. If I open any multimedia item (mp4, mp3, midi, mkv, etc.) I give “VLC Media Player” the highest priority. However, within seemingly irregular intervals another app just “takes over”. It could be “Dragon Player”, “Celluloid”, etc.

Is there another way of accidentally changing software priorities that I must have been doing?

I think I improperly explained my issue. So, If I click on a video file, I want that file to be opened with “VLC media player”, even though I do have other apps available. In short, I am referring to “Open with” priorities for different formats.

What do you mean by priority? How are you setting it?

Oh, I don’t mean priorities for running processes, but rather “open with” settings.

I updated my main post to make it clearer as it was a little vague.

I just did a test to associate my Barry’s Emacs with .txt files.
I used the Open With/Other Application....
In the pop up I checked the Always open ... option and then pick Barry’s Emacs.

This setting persisted over a reboot.
I found that the setting is save in ~/.config/mimeapps.list and contains this for me:

[Added Associations]
text/plain=org.barrys-emacs.editor.desktop;

[Default Applications]
text/plain=org.barrys-emacs.editor.desktop;

Check your mimeapps.list and see if your choice was saved there.

Thank you. Now I know where those settings are stored. I will watch out for the “Last Modified” date to see if there are any changes. So far, they are set properly.