If you're using mpv (which I personally recommend) then:
You add your chosen order and languages to the first options parameter found in Options --> Preferences --> Advanced --> Mplayer/mpv
The format is as so: --alang=ger,ita,bul,eng
So for you I assume:
--alang=bul,eng
I tested this myself and it does work, and respects the priority set as long as the tracks have the language ID tag set. Bear in mind that depending on the file, some audio tracks are numbered rather than named which can lead to the wrong track being chosen.