In reply to Robert schmidt.

@Robert: At the moment you can't import or export master pages from one project to another, though this is certainly something we will add in future. However, in the meantime, you can use your project with your preferred master pages as a kind of template: do File > Save As to save it under a new name, then in Setup mode delete all of the flows and all of the players. Add a new flow, then add new players, and your new piece will automatically use the master pages you've edited in that file. You can also import flows from other projects, or MusicXML files, into this file, and the imported music will also follow all of your settings, including your master pages.