The values specified for parameters and the objects specified for inputs and outputs of a UDE instance can be modified at any time. Simply right-click the instance either in the model browser or graphics window and choose “Modify.” This will open the instance dialog in modification mode showing the current values for the parameters, inputs and outputs. Change the values there and click OK or Apply. Modification of a UDE instance has no effect on other instances of the same type.

One cannot modify anything else about an instance beyond the values for the parameters, inputs and outputs. If you want to modify the topology of the instance, then it would no longer be an instance of the given definition. Thus, you must instead modify the UDE definition. See Modifying UDE Definitions.