The Marker Settings properties let you change the shape, size, and color of the effectors that make up a Control rig. By default, IK effectors display as red or blue spheres. See Customizing Control rig appearance for procedures.
Properties window A. Marker Settings
The LookUI property lets you select the shape of Control rig IK effectors. See Changing the look of IK effectors and Changing the look of FK effectors.
By default, red IK effectors are size 75 or 100, and blue IK effectors are size 150 or 175. Use the Size property to change the size of a selected effector. See Changing the effector size.
The Color RGB fields let you adjust the color of Control rig effectors. You can also double-click the Color RGB field to open the Color window and select a new color for the selected effector.