Working with slurs and ties
MuseScore 3.5; Windows 10
I note that when the voice is changed (say from 1 to 2) on notes joined by a slur or tie, the slur or tie remains in the original voice. I suggest it should change with the voice. (I have not checked what happens with exchange voices. This is about what happens with a direct change of voice.)
Another nicety (not related to this matter) would be, when creating a new slur on the lower note of a chord, the slur would be placed below rather than above the chord. For example, I have a chord pair of two or more notes each. The top notes are already joined by a slur. I add a slur on the bottom notes. It gets superimposed on the upper slur and I have to flip it. I shouldn't have to do that. Further, if I select only the first note of the pair, the slur is superimposed above but selected and I can just press X to flip it. But if I Ctrl select the first and last notes of a chord sequence and slur those, the slur is superimposed above but not selected, and I have to first select it before flipping it. In that case I cannot even know whether, when I select it, I'm selecting the original or the new slur, so I don't know which one is getting flipped! And because they're superimposed, I can't even tell visually that there are two slurs there; I just have to trust on experience that I need to do this. Perhaps I could state it this way. If there's already a slur there, place the new slur elsewhere, not superimposed on the original one. Then it won't matter whether it remains selected.
I could take this one step further. I've entered a chord that I want slurred to the next one, so I press S before entering the next chord. The result is a slur only on the top notes of the chord (if the stems are down). I have to go back and enter a slur on the bottom notes. This is a gray area, because if it's a phrase slur it should only be on the top notes, but if it's a voice note slur on a chord (not written in separate voices) it should be on both/all notes in the chord, and there's no way MuseScore can know the difference when doing the entry. So it's probably best to leave that one alone.
Comments
I'll start with ties. When you exchange voices they move with the exchange if they are "in" the voice you are exchanging from. They do have some independence that needs to remain because you can tie from one voice to another or even from one staff to another in a grand staff instrument when you use cross-staff notation.
Slurs are a bit different and can also be anchored to notes from different voices. They could definitely be improved and from discussions with oktophonie it seems making improvements such as those you mentioned and being worked on. Hopefully working with them will be easier in version 4.
According to Tom Gerou and Linda Lusk , "only one slur is needed when there is only one stem per chord". Elaine Gould says "All notes on one stem take a single slur, and not a slur to each note.