When I want to shorten or lenghten stems in Voice 2 (Stems down) to the behaviour is different, if the notes are beamed or single:
to shorten a stem on a single note, I have to press alt + down to shorten it and alt + up to make it longer.
to shorten the stems of beamed notes, I have to press alt + up to shorten the beams and alt + down to lenghten the stems.
Would be more natural to me, if both adjustments would go into the same direction. No big problem, I just wanted to mention this …