The headlight must aim correctly to avoid blinding other drivers and to provide maximum light on the road; depending on how much time elapses between checkups, they should be checked at least once a year, or whenever a new headlight is fitted or front body work is carried out. On each headlight housing there's a vertical adjuster and it can be turned with a Phillips screwdriver through the access hole on the upper back side of the housing. You need masking tape, a blank wall, a level floor, for adjustment. Horizontal tape line should be referenced to the centerline of all headlights and vertical tape should be positioned on the wall in line with the centerline of the vehicle and both headlights, and include common crutch tape. Vehicle should be parked 25 feet from wall, level, with half full gas tank and no heavy load. The high intensity zone should be set two inches below the horizontal line using low beams on; with high beams on it should be vertical centered just below the horizontal line. High and low beams may not be able to have the same perfect aim so the more used low beams with significant safety impact it would be recommended. As soon as possible a proper adjustment should be done by a qualified repair facility.