This tutorial shows some ways you can add your own folders to the FL Studio Browser. Once folders are added to the Browser FL Studio will search these locations for project data when loading projects and that's why they are called 'Browser extra search folders' on the F10 > File options.
Even if you think you know all this, watch closely you just may learn something new from The Guru...
You can add your own Browser folders & customize the name
For more tricks with the Browser see this YouTube playlist.