How to change default version of movie?

[Efficient_Good_5784]

If you don't want the higher resolution to be selected, why on earth are you labeling the resolution for jellyfin to trigger this behaviour? 

Having the resolution in the filename makes it way faster to differentiate which file is which when you're browsing your files on a computer.
Yes, the docs do state how the system works, and I understand that using Jellyfin requires some compromises, but there are people that desire a certain file naming structure so they can identify their files.
It's not really surprising why people would want the resolution a video is set at in the filename when they store multiples of the same video in the same directory.

Is it reasonable to expect people give up that convenience and download mediainfo, then take the few seconds more to open each video's info? Should people start looking at file size to determine which file is the 1080p vs the 4K one?

Again, compromises are made when using something like Jellyfin, though that doesn't mean that people will be entirely happy with the changes to their folder/file structure.