AU dude

I was driving home one night and id decided to use my high beam, i never really use them as i use thoughs super bright xenon headlight which provide so much light, highbeams doesnt need to be used. Well anyways when i flicked it over to highbeams it seemed that there was less light. When i got home i pointed them onto the gate and they were point straight up in the air, not giving any light towards the road ahead. so i popped the bonnet and adjusted them to a reasonable height. The little turning nob at the back of the lights adjusts the up and down direction of both the low and high beam at the same time, why is this? why not have individual nob from low and high beam. I would like to know if the is some correct height at which the low and high beam light should be at a certain distance from a wall? as moving furthur away will raise the beam of the light. And another thing does the lowbeam headlight dim when the high beam is activitated like as with the lower driving lights located on the bottom part of the front bar on some cars eg. ba xr's???

Thanks in advance.

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