I've been attempting to use graph on parent. Why is it that the scale of the parent-canvas is way different than that of the subpatch? Is there a legitimate reason for this?

Also, what are the functions of the settings "X units per pixel" and "Y units per pixel" in the subpatch properties area? I can't seem to change them when "graph on parent" is on and when it's off, changing them doesn't do anything. Thanks