Poser's Inverse Kinematics (IK) engine uses an underlying (invisible) positioning of joints based on their current keyframed parameters to iterate to a solution. Setting joint angles therefore affects the IK solution.

It is often best to first turn off IK on a chain, position all body parts in the chain by bending them a few degrees in the desired bend direction for each joint angle, and then save your work by memorizing either the body parts or the entire figure using the appropriate command in the Edit menu.