Well, I tried that - right clicking on audio in the hope that I could insert Composer in the tree below. It didn't work. I tried with the other audio entries but of course that just put in a superfluous entry below, which would be expected behaviour.
Having said all that, I'm not entirely clear what you mean by "the labels at the top of the columns" because as far as I can see there aren't any.
Anyway, the new view you recommended has worked so many thanks for that.