I'm probably missing something; but I don't see how using the Event List Editor would help with this? It just seems to show the note events for the melody. I can't see any event that would indicate changing the volume level for all parts (EXCEPT the melody?) at once. As I said, this happens when the song ends or is stopped.

Forgot to respond to another question. I am not importing any Midi files. We are using the archive http://www.igidigi.nl/biab/index.html to find copies of songs we want to do (duo with guitar/vocal and clarinet/sax), then modify to suit our needs. Not sure where that song archive was found. My partner came up with it.

Maybe best solution is just to find a different bossa style, if ZZBOSSA is truly "buggy". ?