Lost feature images
Over the years, I've chosen a feature image for each of my galleries as I've gone along, so I have nice looking thumbnails on the page that lists all my galleries. Today whilst tweaking some other things in the organiser, I clicked on 'Settings > All galleries in folder', and I saw a tick box for 'Feature Image'. It wasn't ticked, and for a split second I mistook it for an option to place the feature image at the top of all my gallery pages. So I ticked it, and now all my feature images/gallery thumbnails are missing!
I can't quite understand the purpose of this box where it is controlling a whole list of galleries. All I know is in by turning it on, I've turned all my feature images off.
Please tell me there's a way to undo what I did so that I don't have to sort through 98k images to find 260 thumbnails.
Thanks in advance