Piano keeps playing

I use Musescore to find some music, then I arrange it for Tuba + other instrument(s), for my personal use (like 'Baby, Its Cold Outside' for tuba and violin - my daughter and I will try this).
I usually start out with piano music, then copy the treble line (to the other instrument) and copy the bass line to the tuba line. then I edit the chords to be just notes. I then 'turn-off' the piano part under Edit/Instruments, and listen to how Musescore 'plays' the piece. Usually works. Well, I did this, and the piano keeps playing! I know this will be something simple to fix, and I goofed somewhere, but I cant seem to readily find the fix. Any ideas? Thanks!