yellowing plastic trim

Plastic have a UV inhibitor that gets "burned away" over time. Painting is the best cure as even sanding the yellow off doesn't help the fact that the plastic is compromised.

I use Clorox Kitchen Cleanup with bleach. Spray it on, go have a cold one ... or 2, rinse. Also works well on the AC outlet covers and grab handle next to the door.

I did the same as others paint...one time and it's done

I used Krylon Fusion about 5 or 6 years ago to paint the trim around my door windows. I am amazed how well it has held up even with all the rain we get around here. It still looks better than new.
Amazing stuff.

As others suggested Krylon Paint For Plastic,most big Box stores have it.

As for the door window This is a great addition.

A friend of ours accidently discovered that Windex makes it white again. Who knew?

Careful use of lacquer thinner will bring the white back. But after your going to have to further protect the plastic. Spray paint would be a good start.

Rumor has it a Magic Eraser will bring it back. Can't confirm it though.

I painted mine with a bright white spray paint that is rated for plastics. I bought it at Home Depot (it seems like a lot of new paints are good for plastics). It is a bit of work taping and adding newspapers around the areas that are to be painted but they look brand new again. I did this 2 years ago and they still look great.

Here is a better picture.
Thanks for any advice.