If you are in "optical" mode in the CASA viewer spectral profiler, only the moments sum, mean, and median are offered.
If you want others, you need to switch to "non-optical" mode: Click on the "toothed wheel" icon at the top of the window
(4th from the left), then un-tick the "optical" option and click OK.
Now you should have a selection of more than 10 different possible moments to calculate.