Replacing the cover image on a published journal changes it for readers the moment the upload finishes. It does not wait for Publish, and no copy of the old cover is kept.
This is the exception to the way the rest of the first editor step works. Your title, tagline and body are held back on a published journal until you publish again. The cover is not held back at all.
The upload is the change
When you choose a file, the editor sends it to UNI and writes the address of the new image onto the journal in the same request. There is no draft copy of a cover at that point and no second step to complete. By the time the message reads Cover image updated successfully, the public page is already serving the new image.
Nothing on UNI stores the picture you replaced. Journals keep no version history, so there is no earlier state to return to, and there is no action anywhere in the editor that puts the previous cover back.
The status label is about the words, not the picture
The chip at the top of the editor reports the state of your text. It can still read Published after you have swapped a cover, because as far as the draft system is concerned nothing text-related has changed. Do not read that chip as confirmation that your new cover is still private. See Reading the journal editor's status label.
Save your own copy before you replace one
Because the live page holds the only copy of your current cover, take it first:
- Open the published journal at its public address in a second tab.
- Save the cover image from that page onto your computer.
- Go back to the editor and upload the replacement.
If you have already replaced a cover and want the old one back, you need the original file. Uploading it again works, and it too goes live at once.
Trying out a cover without publishing it
There is no preview. If you want to see how an image sits as a cover before committing your readers to it, make a second journal, leave it as a draft, and upload there. A draft is visible to nobody, so you can change its cover as often as you like: Finding your journal drafts.