To select an effector:

Select it in the Viewer window or click its corresponding cell in the Character Controls Figure representation

To select multiple effectors:

Ctrl-click to select them in the Viewer window, or Ctrl-click multiple cells in the Figure representation

To select all effectors:

Click any empty space in the Figure representation background.

To select all effectors in a body part:

Shift-click an effector within the body part hierarchy that you want to select. For example, Shift-click the left wrist to select all effectors for the left arm.