Pole angle issue

I’ve been trying to rig a base mesh I made but am having issues when trying to add inverse kinematic bone constraints. It works fine until I try to attach the forearm to the arm controller. When I do this the bones in the entire rig change angles. I was under the impression it would only affect the bones that I had selected or those that were directly connected to the forearm. Any ideas on why this is happening and how to stop it?

Set the chain length to the number of bones you want affected by the IK. 0 means it affects all of them, back to the root.

Thanks mate, I couldn’t figure it out!