three sugestions
musescore should 1 - allow you to play one or more tracks solo while silencing the other tracks. 2 - allow you to copy and paste two or more tracks simultaneously and 3 - have a track with mp3 to be able to play the voice while playing the midi music
Comments
1 and 2 are possible already and since long
If you export your score as MIDI, WAV or MP3 then you can achieve 3 by using Audacity.
1) is possible via View / Mixer
2) is possible the same exact way you'd copy a single staff ("track" of course is not a meaningful notation concept) - select whatever you want to copy, Ctrl+C, select where you want to paste, Ctrl+V. See the Handbook section on selection and on copy & paste for more info.
3) is a common request, hopefully it will be implemented someday, but meanwhile, the workaround indeed is to use an external program
In reply to 1) is possible via View /… by Marc Sabatella
thank you, it was a great help