You did not misunderstand, Classicsmiley. Thank you for the information. Amazing how such a SIMPLE process is completely missing from the help file.
However, I think the fact that I'm using a wired keyboard when I still have my Logitech wireless keyboard drivers on board might be messing things up, as the arrow keys have no effect on any brick I have selected (or for that matter, anything else at all). I've tried the arrows, number keys with num-lock off, arrows with num-lock off, arrows while standing on one foot and even arrow keys with my eyes closed (not wise when there's hot tea near your keyboard).
Any suggestions on how to sort this beastie out, apart from the obvious of yanking the Logitech drivers?