I managed to lose my password in a mixup with my password manager. It has taken me a few hours to work out how to reset it. Following the forgotten password link on the sign in page only takes you to a point where you are asked to reset the password on your iCloud user id. If they are one and the same that's ok. Mine aren't. I eventually found the answer: in the settings app choose developer 2 scroll to the end and choose the sandbox apple account 3. choose this and reset