What's the specific name of the Fossil faces that you've tried?
On my Q Marshal, if I select a face such as Digital or the Cory Richards Edition face I can then long press on the face and get into edit mode. Once in edit mode if I scroll up to + Data I'm able to see the tap targets (3 of them) and tap each one to assign a new assignment to them.
thanks for the reply, when i was doing wht u described, when i got to the data part it would not give me the option to change. i factory reset it, now everything works properly.