There's a black plastic toggle at the back/bottom/centre of the light unit. Inside the toggle thing that's used as described above is a black plastic hexagonal screw, easy to see.
Screw goes clockwise to lower the whole unit's beam pattern.
A similar screw hovers around the rear RHS of the light unit, clockwise takes the whole unit's beam pattern away from the (uk) nearside kerb.
I've got a TouraTech cockpit cover fitted which makes em harder to see/photo but you should have no problem as they're obvious once you've spotted them.
Peter