I’ve somehow got my default music font changed and also a tweak I made to the noteheads is in by default…how do I revert both of these to factory?
If you’ve actually managed to change the default music font for new projects, you must have edited your userlibrary.xml file manually, or used a version provided by somebody else that has been manually edited. You’ll need to manually edit this in a text editor to remove the entry for the font.defaultmusic font style.
For notehead types, it should be possible to revert them via the Engrave > Notehead Sets dialog.