With our Lippert system, I can raise or lower the front 2, or the back 4, or the right-side 3, or the left-side 3 independently, but not a single one. (Actually, I'm not sure I can raise all 3 on a side together. Maybe only the rear 2 on a given side.)
There is a procedure to raise or lower one or more independently if the control unit should fail, but that involves using a wrench to manually open the valve on the jack you want to raise or lower, and then using a drill to operate the hydraulic pump. You don't want to go there unless you are dealing with a failure.