I know there are plastics paints specifically for this purpose. I've gone down this road on a few airplanes I've owned where what looks like the exact same type of plastic has yellowed. In that case I used paints from SEM that were color-specific.
I'm looking for the same color matching specific plastics paints.
rustoleum spray paint white gloss from lowes home improvement
Did mine five years ago still look new
Replaced one port lite last year and it is completely yellow from the sun
All the others that were spray painted look like I did them yesterday.