The other night coming home i thought my rear window was open a little so pulled both switches up on drivers door to close it. As I did my daughter noticed my head lights get brighter. I have tried this and it is happening with all window switches. Any auto elec. geniuses' got any ideas?
2016 UK spec.
CX5 2.1 Diesel.
All front lights have Cree bulb upgrades fitted.

 

It could just be due to the fact that you changed the headlight bulbs from halogen/incandescent to something different (if I understand correctly). Closing two windows at the same time can strain your battery, especially if it's old and getting worn. It wouldn't hurt getting that checked/tested.

 

Battery is 6 months old plus if it was putting a strain on battery the lights would dim not get brighter

 

Your battery is 6 months old since you changed it. Not the true age of the battery.
And you thoughts of assuming its state of condition is inaccurate.
The ONLY way to determine and rule out the battery is to have the battery load tested.
Before any electrical diagnosis of any kind is started that is the first thing to verify is the current state of condition of the battery. Many auto parts change store offer FREE battery load testing.