How to change Name on Yahoo Mail...?

Ok so im 15 years old and i created a yahoo email account when i was 10. I had to use my mom's name and credit card number to create the account, because i was not old enough at the time. so everything is in her name..i tried changing my name and it says its Elizabeth, but whenever i send an e-mail it says its from Marion. To make a long story short, i wanted to see if i could change my name, and i also wanted to maybe switch my email address, idk if thats possible, but i would like to just switch it over or link it without having to tell everyone that i made a new email address, does anyone know if i can do that...and could you please walk me through how to change the name of the sender!!?? thanks a ton:)