Stupid question about replacing outdoor wall light
I attempted to replace the hideous lights next to the front door on our new house. Of course, never easy. The box is mounted deep into the wood paneling surrounding the door, so the screws to secure the fixture aren't long enough. I can get longer screws...My real question is the mounting bracket is loose, I know there should be some adjustment to it so I can get it level but then the light fixture still will turn once installed. What am I missing? I have installed lights before and don't remember this being as much of an issue. Photo of the mounting bracket attached.
This is the light. http://www.lowes.com/pd_203264-2121-W091125ROB-1_0__productId=3295064&Ntt=dark+sky+light&pl=1¤tURL=%3FNtt%3Ddark%2Bsky%2Blight&facetInfo=