2009 model-recently bought second hand car

Large droplets inside lamp clusters and condensation, took them off and saturated with water with water collecting up to the reverse bulb. Dried them off and same problem, also noticed water inside upper high level break light, so odd for all 3 to be the same.

Noticed water on boot carpet also. Had a guy put sealant in the two rear lights where the seal is, but still the same problem, with water on boot mat also.

Any advice appreciated thanks