No response? Oh well, just in case anyone experiences this problem now or in the future, I have found a work-around. I found that I can change the parameter buttons using the mouse scroll wheel. This seems a bit counter-intuitive given that the menu is horizontal and the mouse scroll wheel is vertical. Where as clicking with the mouse seemed would have seemed the more obvious thing to do. Not sure if this is intentional but it seems to work.
I did ring up Steinberg technical support today and they were very helpful and kindly sent me an update patch but that did not seem to fix the problem unfortunately. However I am happy now because I can get on with music making and get to the various menus. 