How to change the artwork on Apple Podcast?

If the image hasn't updated on Apple then it may not be conforming to their requirements: minimum 1400 x 1400 px, maximum (preferred) 3000 x 3000 px, RGB, JPG or PNG ( and not the others quoted above), less than 500kB and no alpha channel. Also, you must have changed the file name from the previous image, or Podcasts, which caches the image, has no way of knowing it's changed.

If you care to post the URL of your feed I will check the image for you.

That's not the proper order, spreaker.com/cms/settings/profile is the central distributor of the podcast and its artwork, not Apple. Recommendations are 1400*1400 px .gif, .jpg, .tiff, or ,png >512kb

The image is OK, though of course I don't know whether you gave it a new file name.

As you say, your podcast is up twice, with different podcast IDs: I don't know how you managed that as it shouldn't be possible. I can't determine the feed URL from the app, so I don't know whether you've managed to submit two different feeds with the same contents, or there's some sort of glitch. Look in your account page in Podcasts Connect and see whether it's up twice there. If it is, you could delete one of them. If it isn't, you should contact Podcasts Support and ask them to investigate: https://podcastsconnect.apple.com/contact-us

As to the image, the only thing I can think of is when did you post it? It can take some days for a changed image to appear, so that might be the issue.

Try this (from https://blubrry.com/support/powerpress-documentation/notify-itunes-podcast-ended-deleted-removed-blocked/)

Sign in to Apple Podcasts Connect and select your podcast’s cover art. On the next page, under Additional Information, select the Delete Podcast link. A pop-up will appear, asking if you’re sure. Confirm and give

Apple up to 24 hours to remove the listing from the directory.