I borrowed a phone from a friend and recently she saw my credit card details on her new phone. She was unable to pay as she didn't have my CVC digits though xD. She also said she could see my addresses, so we guess it's because I've added all my personal data to her old phone which is connected to her new phone.
Reset phone should do the trick? I would rather not do this as I want to keep all my app configurations but if it's the only way.