Edits you make to pin assignments in PinEditor are permanent provided that they are locked and have been committed.
To assign an I/O macro to a pin:
Select the instance in the Ports tab of the Hierarchy window.
Drag the instance to the pin location. If the location is valid, the macro is assigned and automatically locked.
Note: If you assign a macro to a pin that has already been assigned a macro, the previously assigned macro becomes unassigned if it was not locked.
To assign multiple I/Os:
Select the I/Os from the Ports tab of the Hierarchy window.
From the Logic menu, choose Assign to Location.
In the PinEditor window, click each I/O location to which you want to assign the I/Os.