Hi sbapowered!
Have you tried hard resetting the phone, or resetting all settings?
To hard reset, hold down both the Home button and the Power button at the same time until you see the Apple logo, then release the buttons and allow the phone to reboot. (This does not delete anything, it just hard restarts the phone.)
If that does not fix the issue, go into Settings > General > Reset; and choose Reset all settings. This will wipe the passwords for your wifi, but hopefully it will unstick the button for your 12/24 hour time option.
Let us know if either of those worked for you.
10-03-2017 06:19 PM