Thanks Jim, but I'd previously right-clicked everything in sight (left and right sections of the screen), tried every option and could find nothing that would allow me to take 'Playing Now' back to what what it used to be. I wondered whether it was a recent change to the default behaviour but I've just reinstalled 16.0.64 and the behaviour is the same so it's a change to the default that obviously occurred a while ago - just hadn't noticed (not surprising, I've been so damned busy for the past six months have hardly had a moment for my own pleasures...).
Being largely a classical and jazz listener, like many other fanatics, I tag my music extensively. The only way I can get the view I want (sort of) is by using the trees that show in the left-hand column under 'Disk Location' (my music collection sits on my server) and selecting the disk I want to listen to - all the tracks plus the columns I've selected show in the right-hand screen. The CD cover, of course is available only as a small thumbnail when I select display in the bottom of the left-hand column (but is only quite small).
A shame. I used to like the previous default and had it set up the way I wanted. I'd still like to hear if there's a way I can make it revert - or re-create it (which doesn't seem likely). Alternatively, I'd appreciate it if you'd tell me which was the last version of MC that had the previous default appearance for Playing Now - I might revert to that version.