To edit multiple light fixtures, go to
Ribbon: DM Electrical->Devices-> 
Edit Multiple Light Fixtures
Pulldown Menu: DM Electrical->Light Fixtures->Edit Multiple Light Fixtures
You will be prompted to select the light fixtures to be edited.
Select lights to edit:
The Edit Multiple Light Fixtures dialog box will appear.
Edit Multiple Light Fixtures Dialog Box
Changes can be made to the light fixture in the same way as when it was inserted. See the Insert Light Fixture section for more information.