Just to add to this, I find the Allen key adjuster on the front of the light sometimes does not engage the nylon wheel at the back as said, you can help it turn by placing a spare hand at the back of the light and turn the nylon gear and allen key adjuster at the same time, in fact as they are so fragile I would suggest that as standard procedure tbh.
These will need several turns to achieve very little adjustment, so suggest park the car close to a garage door or similar and watch the beam for movement, if it moves sideways you have the wrong adjuster. Once you have sussed which adjuster and which way to turn it(if the adjuster is not broken of course)....
Drive the car as close as possible to a garage door or wall, lights on, mark the position of both beems, reverse up 6feet or so and adjust the beam so the new position sits about an inch below the previous mark.
Note, there is a marking somewhere on the headlight that gives the ratio of dip per distance of beam. By working out this ratio, the percentage of drop from the mark on the door can be calculated from the distance the car is reversed up. But I never bothered with that

Reverse up 6feet and adjust to give an inch drop, then drive the car at night, adjust from there.
Do try to get it right though, too high beam is very annoying.
