I had knee pain once located over the top of my knee cap. Moving the seat back 1/2 of an Inch cured It.

I made two changes at the same time though so there are variables In my case.
I had an aluminum seat post with no set back, moved to a Carbon post with 12 mm of set back.

The knee pain was Instantly and completely gone and the carbon post was like, 'Wow' this thing Is comfy ~

I was able to double my miles and remain comfortable. So was It the set back or the carbon, who knows..