Is there a way to save the mixers track mute status as a global default? I would like to be able to have just drums, bass and piano play by default when I open the program and everything else be muted. Currently, every time I load a new song in it resets the mixer to all tracks on. Thanks!

This is an often-requested item. Please make a post in the Wishlist.

Workaround: while BIAB does not save the Mute status, it does save the track volumes, so reduce the volume to zero on a track you want muted.

I think the 2021 version does save the Mute status, however, it is not global, but local to the song.

That's correct, it saves the mute status into the SGU/MGU file.

You can disable that in the mixer preferences - while BB doesn't save the mute status when closing the program, disabling this option at least makes BB keep the tracks muted when you open another song.