Could you please post a screenshot with the pertinent Panels visible?
If you are talking about the configuration of the shape, You may call up the shape, use the Direct Selection tool to modify the shape & change the H or W in the Options bar if desired, and then Edit > Define Custom Shape. Save the new shape and delete the old one.
You have to use the Path Selection Tool or the Direct Selection tool (A) to change the properties
Thanks for the helpful tips, advice, etc.
I didn't explain myself very well--I apologize.
However, with your tips I figured it out:
When I create a rectangle or ellipse, I can later click on its layer and the Properties window appears with options to change their "Live Shape Properties."
However, not so with the Polygon and Shape tools. With them, the Properties window shows only the Masks, but the Toolbar still shows some basic properties I can change.
I was stymied by the above differences while working only on a Shape.
I've attached two JPEG screenshots.
I didn't need to change the actual shape, just the fill/stroke, etc.
Later, I may wish to change the actual shape, but that appears to be done by simply creating something new.