maybe do some tests and see which setting changes the most, then we may be able to help you
I did tests before my first post and I mentioned which settings were changed without any actions on my part:
-Alarm repeat - Sometimes my Monday, Wednesday, Friday alarms will switch their dates to Tuesday and Thursday (and vice versa).
-Alarm type/tone - My vibration alarms will switch to the default T-Jingle Melody. My Melody alarms will never switch to vibration, however.
-Alarm volume - The volume will be switched back to '4', regardless of whatever it was set to previously.
The only thing I have noticed is that my set ringtone (an .m4a file), often resets to some t-mobile tune.
That sounds similar to what happens to my vibration alarms.