If a single song has multiple audio tracks and you've enabled the option to automatically play the next track, then that should definitely work. However, if you are wanting MobileSheets to play through audio tracks from different songs in order without you switching pages, that will only work if you switch the track list to "All tracks in setlist". I just tested having multiple audio tracks in a single song and letting the first finish, and watched the audio player automatically start playing the second.
Mike
Mike