Beaming, tied chords across bars.
I have two suggestions from my use of musescore:
Firstly, beaming with multiple parts on a stave could be flipped to a common-sense position by default. I get that voices 1, 3 are up by default and 2 and 4 down, but sometimes (usually because of ties from previous bars), I need to use the 'wrong' voice at a particular pitch range. It would be nice if, as one enters notes, the beams on the notes could notice if they are intersecting with beams from other notes, and if flipping the beam on that voice would fix that. If it did that automatically, a lot of time could be saved.
Secondly, when, for instance, a dotted minim is suggested, and a chord using a dotted minim must go across a bar, musescore does not allow you to enter this directly, note by note. Instead one must enter the same chord twice and then manually tie each note. It would be nice if one could make chords going over a bar note-by-note as one would normally.