What might have to do is go to your app drawer and open up My Files. Create a folder in the Media file and name it Notifications and save it. Stay in My Files and find the folder with the MP3'S. Long press on a song and select copy, then go back to Notifications folder and put it in there. Now, back out to home screen and, I think its, Menu: Settings: Sounds or Default Notifications and see if the mp3 is in there with your other notifications. (Something like that) I don't have that phone but it should be similar.