Ringtone keeps changing back to "AT&T Firefly" tone

[smooth4lyfe]

Is anyone else having this problem?
Every time I change my ringtone, after some time it changes back to the "AT&T Firefly" ringtone..kinda being a bother that my custom ringtone isnt staying
Could it be because I used a Ringtone Maker app to create my ringtone? I didnt have this problem with my S4