Why do the settings not "stick"?

Just now I noticed my phone making noises when I locked/unlocked the screen. I do not have these turned on and sure enough when I turned the little switch from "vibrate" to "ring" and back, they stopped. This has happened before.

I've also had issues with the double press power button for camera working. When I go to settings it's still there and starts working again.

Last week I changed my lock screen picture and the Always On Display reverted to the default one. Why would those be linked?

This is my first non-Samsung phone since before the Note 3. Is this just how janky software is that isn't from the big 2? As much as I love the hardware and battery life I'm really starting to regret branching out.