This procedure is a general method of reporting cut/fill values.
There are other ways to report values, including sketching a new surface within an existing surface.
For example, when the view's phase is New Construction, set the Phase Created value to Existing.
In the Edit Graded Region dialog, select Create a new topography exactly like the existing one, then select the toposolid. This step demolishes the original element and creates a copy that occupies the same boundary as the original.
You may need to press Tab to select the copied element.
In the Properties palette, Revit lists the new cut/fill properties for the toposolid.