I'm on Android 4.1.2, in a Motorola Razr D3, and every time the mobile power off, or I reboot it, the default display sleep time will get back to 15 seconds, and I have to set it to 1 minute again, as I want it.
Other configurations like "Language" or "Auto-rotate screen" are not resetting.
In opposite to this question, I did not installed any battery saver software. Although the SmartActions app comes with the phone, and I enabled the "Low Battery Saver" option which would reduce the bright of the screen when the battery is low, I don't think it should affect the sleep time, even more with full battery. I disabled it to test, and there was no change.
Any idea why it's resetting this configuration?