Multiple incomplete measures

Well, you could simply insert a bunch of new measures and copy the original content into them. But, more important than just correcting the length of the measure, somehow you have to correct the contents as well. Almost certainly, some notes are on the wrong beat in each measure. There's pretty much no getting around solving that problem one measure at a time.

Generally speaking, it's usually easier to just re-enter the music normally. People rarely believe when I say this. But often I see people still working on fixing errors in one piece over the course of a week or more, when probably entering the whole thing from scratch could be done in just a few hours.

Assuming you've fixed up the measure contents you could go with https://musescore.org/en/project/time-signature-enforcer.
You can assign it a shortcut and save you the time from going though the measure properties dialog.