Hi rosie,

it works fine, as Dan suggested. A Leftclick onto Water Plane or Ground Plane icon and keeping the left mouse button pressed displays a small pop-up, to select surface or volume. I just verified this in my Pro 7.1 build 109.

Which OS?

Which BUILD of 7.1 Pro exactly do you have installed?
--> Click "Help" to open that menu and then CTRL+Leftclick onto "About".

Hubert

"All that we see or fear, is but a Sphere inside a Sphere."     (E. A. Pryce -- Tuesday afternoon, 1845)