Cannot change artist/album artist

Have no idea as to why this is happening but if I change "Artist" field, The "Album Artist " field changes as well. IE: "How Deep Is Your Love" "Artist 'Bee Gees" "Album" Saturday Night Fever, "Album Artist" Various. Instead of putting Various in the "Abum Artis field it put Bee Gees. It Won't allow me to change the Album Artist field independently of the artist field. I even tried to change the tags in the file itself but it still shows up incorrectly, I even tried to use "blank" in the album artist field and nothing happens, it stays the same. These are the only two fields I'm haveing problems with all others seem to work fine. Also, where can I get the last version of MP3tag. I had this problem before and went back to 2.46, thinking this was fixed I deleated 2.46 and am now using 2.47. I'm terrible at codeing so if anyone has any ideas and it requires coding, please post the code to fix it. Thanks in advance.

Open the extended tag view (alt-t) and check whether the window title has the word APE in it.
APE tags overwrite MP3 tags.
If this is so, open the mp3tag options and uncheck in ape... and mpeg the boxes that allow to read and write APE tags. But do tick the box for "delete APE".
Go back to your track, cut the tags with the context menu of the list view and insert the tags right away.
Then try again to modify.

Aparently somehow I had some corrupted files and once I deleated and installed 2.47b the problem went away so now I'm happy but I do appreciate the help. I've been using MP3TAG for a while and I'm still learning what it can do. Thanks again.