I need a little help with hands.

I recently began playing with jakks figures again and the two joints that are new that I cannot stand are the joint between the wrist and center of the hand/ and joint on the boot. anyway, is there any way to lock those joints so they no longer move?

and one more question... if you wanted to swap hands from one figure to another how would you go about it. (the joint i am reffering to is the one between wrist and hand.)

I am not talking about the actual wrist joint, i am talking about the one that connects to the center of the figures hand.

Thanks for any help you may have.