Look, if authorities really want to find out what sites you've visited and what you've said, having your phone is irrelevant. All they need to know is who your service provider is. Your service provider, Google if you use them, and other search providers, too all have your history stored on their computers. Obviously, just your family or friends wouldn't be able to access that info, but authorities could with a warrant. To keep your SS info private from family or friends, just destroy your phone, or "lose" it. But, remember, all your info is still out there, even without your phone, and can be uncovered by authorities. Would they share it with your family if they obtain it? Idk. It's the Internet. Nothing really ever "goes away".