For some reason, all my default runways have these high-contrast white markings. I'm not sure how to get rid of them. I installed REX, but that only changes the runway, not the runway markings. I've tried changing around my settings, but the problem remains. Any ideas? Help is greatly appreciated.

If you have installed Rex Essential there are option in airport Environment to change runway marking even the old rex have this option.

Anyway it's not that bad you can always find the airport :)

Yeah, that's nasty. I always thought they overdid the markings, Of course since FS treats the runway and markings as separate layers it's hard to get the right effect but still. Wish someone would try a little harder.