animation help

I´m new to unreal engine… there´s a lot I need to learn.

One problem I´m facin atm is that I´m trying to customize an idleanimation to look perfekt when my character is aiming down the sight.
So what i´ve done is double clicked on that specific animation within the asset browser.
I get up a window where I can manipulate the bones and tilt the head and rotate the arms so he has a perfect idle-pose-animation, looking down the sight of the weapon.
Now… what happens is that every one else of my animations gets the same modification… i.e. the jump-animation now has i tilted head when he jumps…

How would I continue to be able to edit this specific animation without affecting the other. Is it even possible. Do I need an external animator software?

grateful for feedback

Using an external software would be the cleanest way.
But if you just want to do a quick hack:
In your animBP, wherever state you are playing that animation in, hook up a bone transform node and do those tweaks in that node(s).
That way youll only have those manipulations happen when in that specific state.