Set the project surround format
You choose the surround format you want to use for a project in the Audio project settings. By default, a new project is set to 5.1.
Choose the project surround format
Choose File > Project Settings > Audio (or use the Open Audio Project Settings key command, default assignment: Option-U).
Choose a format from the Surround Format pop-up menu.
Tip: Save a project that has been set up for surround format work as a template. This way you won’t have to set the surround format every time you want to create a new surround project. Start with the included templates, modify them as necessary, and save them as your own templates.