I just bought these 1pc jdm headlights and have found out that there is condensation inside the lights. Does anyone know how to fix this? Should I seal or caulk the lights? Please let me know what you guys think. 
dry them out really good (pull them out and dry them off, maybe use a hair dryer?–just make sure you get all the water out of them), you can check the teg tips–there is a how-to on how to get condensation out of the taillights. the same basic procedure can most likely be applied to the headlights.
just use some silicon sealant to seal them up again.
Thanks! I’ll do that. 
Also check the rubber seal that runs around the top of your bumper, and underneath the lights. Mine is starting to warp on both sides, and is pulling back from around the side marker lights. I’m starting to get some leaks in my lights too…
Exactly what colin said. Silicone those suckers up. I made sure of all the seams to be siliconed up before i installed them on.