Filename automatically changed

Hi all, first I'm sorry if I don't speak english very good, I'm french, so I hope you will understand my problem :

I use often Mp3tag to change the basic tag of my music easily but sometimes, I don't know why, after I changed tag and after closing mp3tag, my filenames are changed like this : Artist - Track - Title - Kind of music but I don't use the tools to change my filenames (Tag --> Filenames) and in spite of myself, they change I don't know why. For example, I change the tag of Gangnam Style, the filename is "Gangnam Style", and after it changes to : "PSY 03 Gangnam Style K-Pop".

Thanks for your help and sorry for the inconvienence.

As MP3tag does not have any manipulating functions or actions that run by default it has to be something in your environment or your workflow that causes this effect.
And as I cannot look over your shoulder from the distance, I cannot help you any further.