Sorry but I didnt find the answer.
I used Mp3tag and successfully placed a cover on a mp3- put when I try to change it (delete tags add a new cover) then the old cover still appears- wich is strange. Also sorry for my english
Where do you see the old cover?
If it is only the player, you have to clear the cache and update its database.
In MP3tag you can see how many covers are embedded. You can delete them all or individually.
When importing new covers with an action, then tick the option to delete already existing covers.
I'm having the same problem. I'm updating covers and they appear updated in my media library, but when played in the player the old art appears. I've cleared media player history and caches as well as appdata from windows and media player folders.
...what about old folder.jpg files in the individual folders?
I've checked that as well. I may have found a solution just now, though. First, I updated to the latest version of Mp3Tag. Then, I tracked down all the files that weren't displaying the correct art and moved them into a new file folder. From there, I dragged and dropped them into Mp3tag and checked them individually. Each had an amazon.com song id in the comments. I deleted the comments, removed the cover art, and re-saved the file. After that, I tried playing file again and the correct artwork appeared.
Not sure which of these steps solved the problem, or if it was a combination of all of them.
It didn't work after all. when I copied the files from the new folder back to the original, the old artwork showed up when the file was played. However, the files in the new folder showed the new artwork when played.
If something works sometimes and sometimes it does not, it is a detective's job to find out what the differences are.
Which player do you use?
Have you deleted the old files from the library before you put back the new files into the old folder?
Does MP3tag always show the correct covers?