Uploading article cover image for published articles

Is there a way to upload an article cover image to an already published article from the back-end or in any other form?

It doesn’t look nice to have the cover image just in some of the articles

You can add article covers by editing a submission and clicking the metadata link from the upper right corner.

There is a Cover image selection under the list of contributors.

Another alternative is of course to just use issue cover images and not add cover images to single articles. But this is of course a matter of taste.

I have a problem with uploading images for cover image, it upload as you can see in picture
but it dose not apear in article page as you can see below,
whats you Idea about this problem ?

after submit form … failed or success?