In order to protect your personal information, you can adjust your phone’s lock settings by accessing the main menu and selecting: “Settings” -> “Security & location” -> “Screen lock” and then touching the type of lock you would like to use.
After you have set a lock, a lock screen displays whenever your screen is woken up, requesting a pattern, PIN, or other specified key.
Note: Screen lock options are listed in the approximate order of the strength of their security, starting with “None” and “Swipe”, which provide no security.