Hello,
Most schools officially will consider the highest score, though they do see the other scores. And those other scores will sometimes factor in to their holistic review. You will need to check each of the schools for the specifics. Whether the interviewer will know the scores depends on who interviews you and the interview process. If alumni or students interview you, they will usually not have read your application. If the adcom member interviews you, it depends – sometimes they will have read your application, sometimes not. Here too, you have to check each school’s policy.
That said, I would consider the 680 very low for Columbia and low for the other schools as well. I can’t tell just from the GMAT of course, but I would surmise that you probably should be viewing schools like Cornell as your
reaches and target some other schools a tad less competitive also.