I normally copy the Roster file I want to edit into another folder, edit everything I want, save it often. Once you are done and saved it the final time make sure you close AMP so it writes the roster*.db file into the roster main file, then you can copy that roster file back into the Madden20\settings folder. You can also edit it right in the settings folder if you want, just make sure you make a backup everytime you edit it so if the last edit you did messes it up you at least don't have to start over from the beginning.