You can set the following preferences in the Kinematics category of the Preferences window.
To return to the default factory settings, choose in this window. Note that this resets the preferences in every category in the Preferences window.
Changes the display size of skeleton joint sizes. The range is from 0.01 to 5.0.
For skeletons with blended inverse and forward kinematics (IK/FK) animation, this option sets the display size for the joints and bones in your IK and FK skeletons. This option does not affect the display size of the joints and bones in the IK/FK Blend skeleton.
Changes the display size of IK handles. The range is from 0.01 to 5.0.
For skeletons with blended IK/FK animation, this option specifies which skeletons appear in the scene view.
Only the IK/FK Blend skeleton appears in the scene view.
Only the IK skeleton appears in the scene view.
Only the FK skeleton appear in the scene view.
The FK, IK, and IK/FK Blend skeletons appear in the scene view.
By default, joints and bones appear dark navy blue. But when a skeleton has both IK and FK, each skeleton appears as a different color (FK is Black, IK is a Dark Red/Brown, and Blend appears pink/magenta.