Animation Glitch!

I’m trying to get my character to aim. But whenever I correct the animations, such as rotate arms and move hands because they are detached or out of place. It also affects the other animations, such as their hand will rotate and detach. And some how I also can’t apply the animations, whenever I play the game it won’t show the animations/ the ones that I’ve corrected. I’m seriously confused and don’t know what to do!