Trouble with riging and animation.

Hello everyone, I have a problem.

I set up rig to a human in Blender and created IK for the arm and it work great, but to create a more realistic animation I need some times to use FK animation but when I apply IK I can’t rotate bones inside of the IK chain.

Can someone please give some advice how can I rotate them separate but still have the Ik on them working? If to be short I want to use FK and IK together but just don’t know how I googled it but didn’t find an answer.

Looks like I was asking wrong questions to google, I wanted to use IK together with FK and this is impossible, but it is possible to use them buy switching between them.

Here is the link on the tutorial how to manage this.

I am not going to mark it as right answer, just want to check incase someone else has a better solution.