Before you start adjusting your headlight boxes, you MAY find that the front cap has become disconnected from the u channel (metal) support . It was epoxed from the factory.
At the exact center of the front cap, between the 2 headlight cans and near the front edge of the hood-push down with your hand. If there is movement, your cap has become unattached and this will allow the cans to scratch the outer edges when the lights are moved up/down.
Another way to tell is to look at the car from 20 feet away. Follow the hood line to the front edge. When the hood stops and the front cap begins it should be in line with one another. If the front cap is 3/8 inch (or more) higher, your cap probably needs work.
Like you I was looking for a way to adjust the cans to stop the scratching (before I went to paint). After much research I found the cap had become seperated from the u channel. With an improvised tool ( a hacksaw blade with duck tape to make a handle) I had to remove the factory epoxy, sand the u channel, and apply new epoxy then c-clamp the cap to the channel overnight.
Hope this helps.