Armature duplication causing problems I'm currently learning about rigging, skinning and animating, but I've run into a problem with a part of my armature. The scale, rotation and position of my mesh and armature on right side has been applied, I've duplicated the armature for the arm, hand and fingers, mirrored it to the left side on the X axis, but for some reason a part of the arm is twisted. I tried resetting the rotation, scale and position using Alt + G, R, and S, which has helped, but it's still not right. To begin with, the arm was twisted round like a sausage. This is what it looks like now:
You need to correct the IK Pole Angle value of your forearm:


First, select your armature and in the Properties panel > Data > Colors go back to Default Colors so that you can see where are the constraints. You can see that your forearms have an IK constraints (green bones).
In Pose mode, select its right forearm (the one on our left) and go in the Properties panel > Bone Constraints. Now play with the Pole Angle value to correct the rotation. You often needs to do this after giving an IK constraint so that Blender knows how the bone is supposed to be oriented.