If you'd like you can just tell the photographer directly.  You can get his contact info within the app by simply proceeding to MENU > BOOKINGS > UPCOMING > Here you can call, text, or email your photographer any specifics.  At this time we do not have editing.  We're about to issue an update to allow you to add time, bonus, and include ability to edit details like location, dates, etc.  For now, the work around has been for customers to simply cancel the job and request it again with the correct information.