If he can log in with your user name and password he won't need to do the factory reset so let's look at that as being the last resort. As you log in with your hotmail email address you can change it on any computer that you can get on to the desktop hotmail site on. I've never found full settings on a mobile or tablet version of the site. You would need to go to outlook.com and sign in with the hotmail email address and password. If your password works on that page then he's definitely not typing it in correctly and I'd leave it as it is and get him to make sure the caps lock key isn't on or something like that. If it doesn't work then you'll have to go to the hotmail reset page at this link https://account.live.com/ResetPassword.aspx