I don't have P7, and I don't know what's causing your problem, but the "Offset" dials are for moving the 'origin' (a.k.a. "Center Point"). P6 should really display these as well, but it's a bit flaky in that respect. Initially the values in the Joint editor should be the same as the values on the Offset dials. If you move the origin with the dials, you may have to save (either to pz3 or cr2) and reload your figure before the changes you made show in the Joint Editor.