UI Suggestion: dynamic range "Part": use "Instrument" instead

The term "Part" is used in MuseScore all over the place, and in the vast majority of cases to mean Instrument (or voice, but then in the sense of singing voice, Soprano, Alta, Tenor, Bass, etc.)
Changing it in just one place would lead to even more confusion. And I've never seen Part being confused for Voice?!?
But see also #58031: Dynamics/hairpin range for Voice, once that'd be implemented that possible confusion would certainly no longer exist

Maybe a better documentation in the handbook might help? Although IMHO https://musescore.org/en/handbook/3/dynamics#adjust-range is pretty clear on this topic

Consider that a Part may contain more than one instrument on separate staves. That is very common in light orchestral wind parts for example where you often get flute 1 & 2 on a single part but each with their own staff and each having their own dynamics.

Also, for instrument + piano accompaniment pieces, I usually find it more convenient to create a piano+instrument part in addition to the full score. It means I can have everything full sized in the score making editing easier but have a small instrument staff above the piano staves in the accompaniment part. Again, piano and instrument would obviously need independent dynamics.

Instrument rather than "part" would be a more accurate terminology, but having said that, personally I have never been confused by the current wording.

In your case of combining more that one instrument into a part (via Add staff rather than Add instrument), Part is the correcte term in connection with Dymanics range, as it affects all staves of that part.
Part int the sense of File > Parts though indeed is a different thing, such a part can have more than one instrument (or part, to make the confusion complete), like in a Closed Score SATB + Piano you may a a Piano part and a S/A+T/B part (which, to add to the confusion are also voices, Women resp. Soprano/Alto and Men resp. Tenor/Bass)

No, I don't mean that there are two staves for some sort of mutant double flute instrument. I mean that there are two independent flute instruments that have their parts written on separate staves, one above the other on a single sheet of paper. Each instrument needs its own dynamics. Or to put it another way, it is not always the case that both instruments of a woodwind "pair" have the same dynamic.

Then each flute is a part of it's own, as far (as dynamics are concerned)

😉

Yes, but the OP's point was about what we call the range of a dynamic - "part" or "instrument". My point us that a "part" may have more than one "instrument" and giving the impression that a dynamic affects the whole part may be confusing as where there are two instruments on a part they need independent dynamics. Currently this would need those independent dynamics to have a range of "part". The suggestion is that dynamics that affect one instrument should have a range called "instrument". That would be more accurate. But, while the current naming might be confusing to some, it is not confusing to me.