Welcome to RV.net!
The center point on the lamps should be the 12 volt source. If you bought the small plug in type fixture, it should not matter.
The porch light should be connected to the TT battery.
There should be a junction box under the tongue of the trailer. Check there for problems.
What is the clearance lights using for ground? Some rigs use the metal skin as the ground return.
What is make and model of TV, TT and lights you are using?
Some TVs have individual fuses to power turn signals and taillights. Some have the fuses under the hood.