Fans have also suggested the stations were "configurable" (in universe). The crewperson would press a certain sequence of command buttons that would then change the functions of the remaining controls.
As for "labels", someone suggested the more "prism" like buttons might display text that's viewable from a relatively narrow angle, say from the standard sitting position. Since we as the audience rarely saw the stations from those angles, we just don't see the text.
Hey, if nothing else, these questions indicate your kids are interested and want to suspend their disbelief.