To update a saved widget - first you need to drag the widget you want updating into a Pod.

Then make the changes you want to this widget.

Then click the Save icon on the widget, and then the 'Update Widget' button.

Note - These changes will only be reflected in that current widget, and all new uses of that saved widget going forward.

Note 2 - If you change the name of the widget and then click update it will rename this widget.