The acces to screws is from engine space, and there are holes to insert the phillips screwdriver who needs to be LONG as the screws are deep inside, then if you reach the screws the procedure is rather easy: put the car in front of a wall and sign the height beams are, then go in reverse for some meters and beams have to be lower (10% on 10 meters, more or less), in no way they have to be higher. To complete the procedure you need to control if direction of beams is correct, reversing straight they don't have to go left or righ , if not there are other 2 screws to move. Alle these settings request some complete turns to be effective, being the movements of beams very light, anyway it's a good practice ti keep in mind how many turns you do so to come to previous settings if finale effects is not satisfactory.