Very often we see the cover of the album or the single when we listen to an MP3. But other times you may not see it because our music player has not found the artist or because the file has been downloaded ..
To remedy this, you need to use a tag music program with which we can change both the cover and the other data in the file: artist, title, genre, text, etc.
The best music tag program is mp3tag. It is necessary to drag the files into the list and insert the necessary data remembering before clicking on the specific track of the list that interests us. And infinitely save ..
I also list some alternatives to mp3 tags:
MusicBrainz Picard https://alternativeto.net/software/musicbrainz-picard/