To edit the UCS, double-click the UCS. Alternatively, select UCS and click Redefine Feature from the context menu.
Specify the UCS position relatively to the Origin, or, in a part file, also relative to the existing geometry. Heads Up Display (HUD) shows values relative to origin of UCS.
Click the UCS triad origin and move the UCS to a new location. Or, click the axis to rotate the triad around the selected axis. You can also click the arrowhead to move the triad along the selected axis.