Cannot delete erroneous album artwork

If iTunes is doing a poor job of finding the artwork I suggest that you forget that idea and do it yourself.

There are two methods that I use, one of which is not as obvious as it should be:

1. 1. find a copy of the artwork that you wish to use and save it to your computer, the add it later (see below)
   2. copy and paste the artwork from wherever you find it online (the not-so-obvious method)

To add artwork to:

• • one song, simply select the song
  • to add artwork for multiple songs, click the first song, then hold the shift key down and select the last song so that those songs become highlighted in blue

• • once highlighted, from iTunes' top bar menu, choose File/Song Info (or right-click/Song Info) for one song or File/Get Info (or right-click/Get Info) for multiple songs. This will open the dialogue on the Details tab
  • select the Artwork tab
    • if you have the artwork saved on your computer, click the Add Artwork button (on the Artwork tab) and navigate to the picture you want to use. Select it and tap the OK button
    • if you are using the copy-and-paste method, copy the picture from your source and go back to the Artwork tab in the selection. Here's the not-so-obvious thing: as far as I can tell, the only way to paste that picture into the songs is to use the CTRL+V method to paste the artwork into the selection (i.e. hold down the CTRL key while tapping the V key)

I tend to use pictures that are somewhere between 300x300 and 600x600 pixels in size.