I've been having this problem with my sound notifications ever since i updated to ios10. My sound notifications, especially whatsapp and snapchat, keeping switching from the tones i have set, to the tri-tone sound. i have rebooted the phone by pressing the home and power button simultaneously till the logo appears, everything is fine then after a day or so it will switch to the tri-tone. Any way to keep this from happening permanently? any help will be greatly appreciated.