Q: Apple id passward is changing everytime

In the last year, I have Been reciving mails from Apple that said that my passward of apple id had Been change from an ipad. I had made everything already  to make my account as secure as possible, I already change mi security questions, my hotmail passward, my iPhones passward, used passwards very difficult, but it continues changing and I dont know What to do? I need a solution that doesnt include to make a new apple account because I have a lot of staff on it, músic Pictures, application, contacts, etc. Please help me!