Hit the Cancel button on the Edit Settings Screen, and ask the customer to shut down their desktop.
After the customer tells you they have powered it off wait about two minutes and hit the Refresh button in the top right of vSphere.
Select edit settings on the machine again.
You should now be able to change the number of displayed to the amount requested by the customer by expanding video card, selecting the number of displays, and then pressing ok.
Hit edit settings one more time, and select Power On.
Note: Wait about two minutes to allow to desktop to initialize.
Proceed to the next step.