When changing units while bodies are selected the volume and area units don’t update correctly. The symbol for square meter or cubic meter will change, but the value stays the same. In order to get value updated you need to deselect all then change the unit you want it to be measured in and then select again bodies you want to measure.
In first photo I have selected units in centimeters and in second one I’ve changed them into meters and the only thing that changed was the symbol of the units shown.
