cover tag

I have the wrong cover attached in all my mp3's
I have selected the cover I want with extended tags but it won't rewrite it.
In the cover block bottom left corner, there are three options and one is right but I don't want the others.

Where do you see the wrong cover?
In Mp3tag or your player or the Windows Explorer?

From the sound of it, I've got a similar issue.
When I play a particular track (in this case with VLC), the wrong cover art is shown in the player.
In MP3Tag, what happened is this:
I added an Album name (Song - Single)
I added the wrong cover art.
When I realised this, I added the correct cover art and replayed the song. The wrong cover art still showed.
I took another look, and saw I had multiple covers in the tags, as shown by Mp3tag.
I removed the additional (incorrect) covers via 'Right click > Remove Cover' until all that remained was the correct cover.
I replayed the song. Still the wrong cover.
I removed the album tag. Replayed. Correct cover.
Re-added (same) album tag. Incorrect cover.

If OP went through something similar, then it is likely that the album is linked to the incorrect cover. Now all we need to know is how to remove this link.

VLC stores the cover in its own cache when you play a song for the first time. It also looks in the internet for a cover if it doesn't find a cover in the file and you don't disable that.
Go to the folder %appdata%\VLC\Art and delete the special cover or all covers if you want, because there may be a general corruption.
If you play a song, VLC looks for your cover in the file again.

I tried 6 different methods outlined in various forum posts without luck. Here's what SEEMS (so far) to be working. In MP3TAG right click the image and "Remove cover." (BTW: There can be more than one image. You will see something like 1/2 with arrows below the image.) AFTER removing the existing cover delete the ART folder in "%appdata%\VLC\art". Then add the correct cover.

In another thread I was told I could select ALL the files and then "add cover." I tested that with just a few folders. That added the correct cover some of the time and others got the artwork from the first folder selected.

If you could tell us which methods you used I could try to help you to analyze what went wrong.

What I can tell right now: it is absolutely irrelevant which covers are embedded in a file if you want to clear the VLC cache. You can clear that cache any time you want, it is not required to remove embedded pictures first.

In respect to your complaint that you get the covers from the first folder that you selected:
see your other thread for the better way to import covers: Album art