Modify an animation doesn't work?

Hello,

I had encountered problem with the modification of my animation.
The only thing i want to do is to move bones (like arm or finger) of my third person character.

I already done the retargeting skeletons based on the default third person character.

The problem comes when i try to save all of my modification, there is no alarm and no error, it’s just that nothing have been modify (it come back to the default skeletons).

I am new on Unreal Engine so it’s possible that i didn’t understood the concept behind the animation.

Thanks for your help