After creating cover, other divice don't show it


My problem is about the cover editing. I'm currently changing all the covers for my music (because some are totally wrong and other don't have one either) and I am facing always the same problem. After deleting the old cover and editing it to the new, the new cover won't show up on my smartphone after putting the edited music file from my computer in to my smartphone.
Is there something I need to click (options etc.) or is this something different?
Would be nice to get some help, I am exhausted always seeing the old covers...

Thank you and have a nice day!

see e.g. here:

or here:

What happens if you rename the files slightly, e.g add an underscore at the end?

I have checked when this problem occurs. When there was a cover before editing, it won't show the new one. If there was a blank one or nothing at all, it was perfectly fine.
I'm deleting the old covers before choosing the new one, so why does it only occur in this case?
Changing the name slightly didn't work.

I would assume that your player has some kind of cache or database where it saves tag data. So you would have to find out how the player can be triggered to read the new data.
I would have thought that renaming a file and then importing it as a new one would force the player to read the tag data. But as I don't know how and where you renamed the file, it is up to you to investigate a little further.
And to make it all clear: this is a player problem, not an Mp3tag problem.