Instrument change key signature issues for other (not changed) instruments

Issue type

UX/Interaction bug (incorrect behaviour)

Description with steps to reproduce

1. In a bigband score I change the wind instruments a few times.
2. Sometimes - tho I don't know what is the deciding factor here - an instrument change (eg. Bari Sax to Bass Clarinet) appears a key signature(-change) for all instruments not just the new Bass Clarinet.
3. If I try to delete the key signature (on a different stave) I get a popup wich tells me that the key signature can't be deleted. But somtimes all, or only some of the wrong key signatures disappear after that.
4. After saving the key signatures reappear
5. Sometimes these keysignatures are also wrong (e.g. the Clarinet changes from 3 flats to one flat in a concert pitch score although it had nothing to do with the instrument change)

Supporting files, videos and screenshots

I cannot upload my screen recording but here is a link

In which versions of MuseScore Studio is this issue present?

4.6.5

Regression

I was unable to check

Operating system

Windows 111

Additional context

No response

Checklist

• This report follows the guidelines for reporting bugs and issues
• I have verified that this issue has not been logged before, by searching the issue tracker for similar issues
• I have attached all requested files and information to this report
• I have attempted to identify the root problem as concisely as possible, and have used minimal reproducible examples where possible

Reproduce the report in MuseScore Studio 4.6.5 using a bigband score with repeated instrument changes, then observe key signatures on instruments that were not changed. The fix is done when unrelated staves retain their correct signatures, deletion behaves consistently, and the result remains correct after saving and reopening.