Is there a way to change the notification to a custom sound and not the ones they have?
Yes. Use Zedge.com or the Zedge app; you can search and find hundreds of customized ringtones and notification sounds, download them, and then use them in place of the stock ones. I love Zedge! And it's free.
Another option is to use any .mp3 file that you may have; just place a copy of the file in the phone's Notifications folder in the phone's internal memory.
