Regression: No Page Settings for Parts
There is no way to change the page settings for individual parts. The page settings dialog only functions for the primary score, and allows you to flow changes down to all the parts or not, but there is no way to change the page settings for individual parts. It makes sense to me that page settings affects the page settings for the MuseScore tab that I am viewing, considering that I can export and print just that tab. There is already a feature to apply the score's page settings to all the parts, but there is no way to make them different.
As a hypothetical use case: There is also no clean way to make the score one page size, and all the parts another page size. There is a workaround: applying a page size to all the parts, then resetting the page size of the score, but that's not straightforward. See the attached score. The score is tabloid size pages, landscape, but I might want to make the parts letter or legal size, portrait.