Ok, some close ups would help. But I will go on my experience.
Normally they are not really screws. The tops will be a HEX head, so you need like an allen wrench to turn it. Sometimes you can physically see the tip of a screw poking out the back of the light so when you turn the HEX head the screw turns. Also the HEX head is normally off color from the rest of the headlight housing. So it should stand out.