Park on an incline and the bubble will change. You can't really tell by that unless you know for sure you are on a level surface. I just point mine at a wall and judge from that. There are three knobs on the back of the headlamp assembly to make adjustments. I can't remember which adjusts height. I just turned them on and turned one and watched what happened. Sorry I couldn't be more help than this. Didn't feel like going out to the car and figuring it out.