To expand on what MF said: Middle button trims motor, under power. The motor has a trim limit switch which is adjustable, to allow for trim. To tilt the motor for trailering, push middle and top button together.
Bottom button is for down.
Note: A lot of those trim limit switches break. They are PIA to repair or cannot be repaired. In that case you can bypass the trim limit switch and use the buttons as designed, or simply use the tilt function for both trim and tilt.
