After altering “Engraving options” and “Notation options”, how do I set both back to their factory defaults?
For an existing project, unfortunately there’s no good way to do this at the moment, though it is something we will add when we come to work on the import/export of libraries of settings and entities etc. between projects.
If you’ve saved options and want to ensure they don’t get applied to new projects you create, you can delete the files engravingOptions.xml and notationOptions.xml from ~/Library/Application Support/Steinberg/Dorico.