1) Go to this URL - https://foswebapps.stellar.aero/passwordreset/showLogin.cc
or if you are using FOS for the first time, you will be forced to enroll when you click on the FOS app and then click "Enroll".
2) Sign in with your email address and password for Stellar Cloud.
3) The default method of resetting passwords is using a Verification code. Enter the email address(es) you like to register to have a code sent to you. We suggest at least 2 email addresses.
3a) (Optional) You can also use security questions to change your password. You will be asked to pick 3 questions (or make up your own questions) then provide an answer and click Enroll.
4) You are done. Just click "No".