You change it the same way you did in Object Info in the older versions. Click the units next to one of the position boxes to cycle the units until you get the ones you want.
Oh for cry Pete!
I was trying to do it with a mod key -- that is, holding down CTRL to actuate the change instead of just clicking on it (though I do think I tried just clicking on it at one point...maybe I was not right on top of it...). Sorry, Phil. File this under embarrassing.