To modify a junction box that is inserted on the drawing, go to
Ribbon: DM Electrical->Devices-> 
Query Device
Pulldown Menu: DM Electrical->Modify Devices->Query Device
Select a junction box on the drawing. The information in the database regarding the selected junction box will be displayed in the Query Junction Box dialog box.
Query Junction Box Dialog Box
Changes can be made to the junction box in the same way as when it was inserted. See the Insert Junction Boxes command for more information.