changing Project Title

Please advise on how to change the working title of my manuscript. I’m in Non-Fiction mode, on a Mac. I tried changing it in MetaData, but that didn’t change the title at the top of every screen’s page, and my old title needs to disappear!

Do you mean the name of the project file itself? If so, just close the project (important), and locate it in Finder, changing the name there. That’s all you need to do!