As you are adding units to a quote/order you can view the panel list of that unit:
Right-click on the unit product code, select Components... from the pop-up menu and click Panel List.
From this screen you can 
add, 
delete and edit the dimensions. (If you add a panel here you will need to enter the dimensions manually). Click 
Update if you have made changes and close the window.
For further panel lists see the full Cut List local settings.