I'm sure that thread title has you rolling your eyes, and I don't blame you! I was messing about over the weekend with adding a custom column for collections on my Kobo (that all worked perfectly after a little trial and error) and somewhere along the way I think I messed with a display setting for the "Edit Metadata Individually" option.
It used to open a fairly large window that included an image of the cover and (crucially for my purposes) a section where you could remove/change the cover by searching metadata sources. Now when I edit metadata on individual books, I get a much smaller window that only includes a handful of fields: Title, Title Sort, Author(s), Author sort, Series, Number.
Those are in two columns and on the right is a field that displays the various formats for that book, along with some buttons, one of which is "set the cover for the book from the selected format" but that doesn't give me the window with the various options to choose the one I want.
I'm probably explaining all this badly, so please ask questions if I'm not clear. I looked in the "Look and Feel" section of Calibre's preferences and didn't find anything that seemed right but perhaps I'm must overlooking something glaringly obvious. In which case, if you could take a pause from
to type out a response that starts with "Hey, knucklehead, it's [obvious solution here]", I'd be grateful.