Adjusting an animation The animation of the arm needs to be rotated slightly

Hello I have a motion capture animation applied to a base mesh as in the clip, however the animation needs to somehow be rotated on the arm - so hes not burning his ear...

is it possible to rotate the arm somehow without affecting the rest of the animation?

Side info...
I'm not an animator, so the graph editor is a bit of a mystery to me.

Animations are imported on the FBX and thus lack animation controls...

With thanks 
Natalie
You really should open up the Graph Editor...

I you select the arms, you should be able to uncheck all animations at first by clicking the upmost EYE icon



Then select one (open the eye) of the rotation channels (you may have X Y Z Euler Rotation unlike in the image). Then keep your mouse cursor over the curve and press A to select all keys, then press G to grab them and then Y to restrict the Y axis and then just move your mouse up or down to adjust the rotation of the arm.



Hope this helps