The menu font size comes from your operating system and should be the same size as other applications. So changing it in your OS would normally be the way. But on some system with high resolution displays and "scaling", sometimes the info isn't communicated properly. We'd need a better description of exactly what is too small and what isn't - ideally with a screenshot - to advise further.
Comments
See: #302538: Why is the font so small???
What version of MuseScore on what operating system?
The menu font size comes from your operating system and should be the same size as other applications. So changing it in your OS would normally be the way. But on some system with high resolution displays and "scaling", sometimes the info isn't communicated properly. We'd need a better description of exactly what is too small and what isn't - ideally with a screenshot - to advise further.