I think: Press SETTINGS, then AUTOPILOT. Then on the right I think there is a toggle to turn on/off "Select active autopilot". I'm not sure as I'm looking at my unit (same as yours) and it doesn't light up because I am not on the boat with it connected to the Xi5.
The AUTOPILOT rectangle on the home screen does show on my unit without being on the boat. When I press it, it opens up with the likeness of the remote with TROLLING (vertically) on the left side of the screen. When touched, it expands and says 'No autopilot computer' as it is not connected because I'm not on the boat.
Hope this helps.
LIVE PURPLE LOVE GOLD