2001-Jeep Grand Cherokee headlights

The plastic lens on both headlights of my 2001 Grand Cherokee are yellowed. I bought a bottle of headlight lens restorer made by Blue Magic and polished the outside but there is no improvement. Do I have to pull the headlights out to see if I can polish the inside of the lens? An auto parts store printed a one-page instructions on removal & installation for me. Can I even get to the inside of the lens with the headlights out? Thanks for any information.

Is there moisture or condensation inside the housing?

You can’t really get inside the housing, but if there’s moisture in there you could drill a small hole in the housing to let the moisture dry out.