Imported midi question | MuseScore

In the screenshot it would appear that each staff has only one voice.
If so, you could follow this procedure:
1) Select the entire second double staff, and swap voices 1 and 2;
2) Activate the filter for voice 2 only, select the entire second double staff and copy it;
3) paste everything into the first double staff;
4) still with the filter active, select with ‘all similar’ only the notes of voice 2 in the first double staff, and move them to voice 1 (Ctrl + Alt + 1);
5) still in the first double staff, select all the rests of voice 2 (all similar) and delete them;
6) repeat the operation for all the other double staves.
If there are polyphonic bars, you need to change the target voice to 3 or 4.
Too complicated?
7) open the midi file in a DAW and merge all the tracks into one…