Run in terminal:
ps -aux | grep -i muse
with either the first and then the last of your MuseScore programs running:
You might get something looking like this (example nheko from repo and poddr as appimage)
sebi@solus ~ $ ps -aux | grep nheko
sebi 2661 0.4 2.1 36692028 340736 ? SLl 17:15 0:10 /usr/bin/im.nheko.Nheko
sebi 10254 0.0 0.0 7080 4480 pts/3 S+ 17:53 0:00 grep nheko
sebi@solus ~ $ ps -aux | grep -i poddr
sebi 9379 5.6 1.1 1216330368 189104 ? Sl 17:49 0:00 /tmp/.mount_poddr.JhOJNC/poddr --no-sandbox
sebi 9382 6.5 0.0 12140 2636 ? Ssl 17:49 0:01 /home/sebi/Programme/AppImages/poddr.appimage --no-sandbox
Maybe this helps to find your program.