knees

i know at address your knees should be bent so they cover up at least half of your feet when you look down...i have always locked my right leg through my swing, iim right handed, and ive just realized thats making me hit thin...are you supposed to keep your right leg at the same angle throught the whole swing...and should your left leg stay the same, i know ive read that your left leg should bend in...please clear this up for me

I'm far from an expert, but I've learnt that it's essential that you do not straighten you right-leg in the backswing!

As the spine tilts at address, the knees should bend naturally to maintain balance, otherwise you will fall over if somebody pushed you from behind. If your spine angle stays the same during the swing, the knees should maintain their flex without thinking about it. If your right knee straightens, you have changed your spine angle. Old school players maintained their knee flex thoughout the swing. Some modern players lock their left knee towards the end of the follow through to give them extra whip. Personally, I think this was the cause of some of Tigers knee problem.

does locking your right knee during backswing cause reverse pivot?

It can if you have to straighten it to lock it. The knees should stay flexed and supple during the entire backswing. A reverse pivot can also be caused by an attempt to kill the ball.

I've always had this problem, mainly I think due to wanting to swing back as much as possible. As a result, right knee straightens and hips turn way too much (during the backswing). Lately I've been trying to swing with the feel to really lock and restrict and right knee and hips. You might think it's too extreme, but that's why I stress the word "feel", because in reality even if I feel like I'm not turning my hips back at all, the video shows that I've turned quite sufficiently.

IMHO, I think working on the feeling of keeping your right knee fixed throughout the backswing (extreme as it might seem) might be a good starting point...