Yahoo Mail Account Name?

The false name I made for myself when I created my email in middle school was Sam Fu, and even after I've changed my name to the right one in my Contact Information in my account and in my Yahoo profile, it still comes up as Sam Fu when I send an email... I'm going into college in the fall and so I'd really like to change it to my correct name instead of the embarrassing Sam Fu. I've been getting a ton of emails lately from various offices and my coach and future teammates so I don't want to get an entirely new email address if it can be avoided. So if anyone can help me change the original account name, that'd be much appreciated. Thanks!