Update book cover after changing it.

I'm probably overlooking this but I don't mess with Metadata anymore. So I'm lost.

I was given some free books through instafreebie they are missing covers. So I use "edit book" to assign the cover which is already in the file. However I can't figure out how to get the new cover to show in Calibre's cover preview. How do I get Calibre to update its cover to match the epub file's new cover? :help:

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