Once a pcell has been instantiated, the instance can be changed to represent a new set of parameter values if the pcell is available. Thus, when a design is exported to another site that may wish to modify the cell parameters, the pcells must be exported as well. The pcells are not automatically added to GDSII files or the other file formats. They can be supplied as Xic cells, in addition to the GDSII or other output. Further, Xic native pcells are not directly portable to other design systems, they are known to Xic only.
One possible way to maintain native pcells is to place them in a library.
Assuming that the pcell is available, one can change the parameters of an existing pcell instance with the following procedure. First, select the pcell instance to modify. Then, while holding down the Ctrl key, click on the selected pcell. The Parameters panel will appear. One can now change parameter values as needed, and press Apply to reparameterize the instance.
Less conveniently, the pc_params property can be edited with the Property Editor with the same effect. Bring up the Property Editor with the Properties button in the Edit Menu. With the editor active, click on a pcell instance. The instance will be marked, and its properties listed. Among the listed properties will be the pc_params. Click on this entry in the listing window, the text will show as selected. Then, press the Edit button in the Property Editor, which will bring up our old friend the Parameters panel. Adjust the parameters, then press Apply. The new parameter set will be applied to the marked instance.