Your side marker has a large clip that you squeeze in the horizontal plane...look back there with a flashlight & you'll see. That side marker has to slide straight forward when its released, as it clips into the side of the headlight cluster.
Removing the marker, you'll see 2 bolts up high that hold that side of the headlight cluster, and down low you'll see a bolt installed vertically that holds that end of the metal fascia. The other end is held by the screw you've described.
If you remove the 8mm bolt near the grill that goes into the inner side of the headlight cluster, the only remaining fastener is the large plastic one up top.
How I adjusted mine recently: I started by aligning the outer edge of the cluster with the fender lines/creases...the 2 mounting screws on the outer side allow some positioning. I next installed the 8mm hex bolt on the inner side of the cluster, paying attention to align the cluster comparably to the other side, as relative to the grille assembly (you may have to close the hood a few times to check). That done, I simply installed the big plastic nut-thing without disturbing the cluster location. That done, re-install the side marker, button things up and go find a wall you can aim your headlights on!
"If everything seems under control, you're simply not going fast enough" --Mario Andretti
1995 E500 street car
1986 Porsche 944 Turbo S track car