My Hampton Bay ceiling fan & light have suddenly started turning on & off by themselves. I have a new neighbor, so I'm assuming they have the same remote codes as I do. I saw someone else with the same post & they were told to change the dip switches. Where & what are these & how do I change them?

They differ from fan to fan, but there is one set in the remote and another on/in the fan body somewhere. See:

http://www.ceiling-fans-n-more.com/ceiling-fan-remote-controls.php