Trying to change settings on iPhone 4s?

I have iOS 8.0 (which I can't update it to 8.1 because I don't have enough space), and some of my settings are changing to the default settings. I've tried changing them back and restarting my phone, but that isn't working. What should I do?

You have to connect your phone to a real computer and use itunes to update it. Then it will work