In play mode, edited character's bone rotations gets reseted, even with avatar mask

Hello, I have a problem of editing character model using bone rotations: each time I try to manually change them, animations ruin it all. I have created an avatar mask to deselect head, right hand and chest, but it still seems to change finger rotations. I am completely lost… Here are the pictures to illustrate my problem:

In the pictures above you can see illustration of my problem.
Note: I control arm bones manually during play mode, except for the fingers (but I tested with and without script and the outcome is still the same locked transform). Also, I tried disabling animator, this helps. But since I have an avatar mask, I don’t see why would it effect the place that is deselected…
So how to apply bone rotations manually before the play mode so that it stays during play mode?
Thank you, any help will be appreciated!:slight_smile:

I just realised the reason… The default avatar pose gets applied if there are no other animations in animator. That’s the reason of messed up poses and rotations.