The following group changes are performed immediately; you do not need to use the Apply button.
Turn on/off - Click the lightbulb to turn on or off a group.
Rename - Click the group name and press F2 or click a second time (slow left double click) to begin editing the group name. Press Enter or click away to complete the change. Note that the Global group name cannot be changed.
Delete - Click the minus sign to the right of the group to delete it and add all its variables to the Global group. Note that the Global group cannot be deleted.