measures per bar
No menu process currently (v 3.2.3.7635) exists for setting the number of measures per bar. Manually adding "line breaks" is not an option. Defaults to 10/bar & looks like shit; want 4/bar, or I might want to set later to 3/bar.
Request description of steps necessary to set 4/bar.
Comments
measures per bar doesn't make sense, as one is the American English term, the other the British English term for exactly the same thing.
If you mean measures (or bars) per system, there is a tool for that in Format > Add/Remove System Breaks, which does allow to add one every 4 measures/bars (and that tool even defaults to 4 measures per system)
See https://musescore.org/en/handbook/3/layout-and-formatting#system-breaks
FWIW, there is no set default for number of measures per system, nor should there be - it totally depends on the width of the measures. Empty measures are naturally narrow and are supposed to be able to fit many per system (with the default staff size on A4 or Letter paper, it will be more than 10). As you add notes, the measures get wider and fewer fit per system without your needing to do anything special to made it happen. But indeed, for those special cases where you want exactly a constant number per system for whatever reason (typically, lead sheets or music for children), then the aforementioned command is what you want.