In the event you're device accounts has been compromised, immediately access your account from a different device and change your passwords. Remove all email accounts from the device >restart your device and reenter your email accounts with your new passwords. Make sure to make a lock code for the device that you only know. Check your app list and make sure there are no unfamiliar apps installed on the device. It may be a good idea to have one or more accounts linked to (a) your Gmail account because in the event someone else logs in from a different device with your Gmail account Google will notify you with the time, date location, stamped.