I had made a yahoo account by d name of Priyanka Kapoor but now I cant make changes....help....?

I had made a yahoo account by d name of Priyanka Kapoor but now I have changed it 2 Priyanka Kumar but still when I send someone an e-mail..it still displays Priyanka Kapoor although I have changed my display name to priyanka Kumar as well as my account name...please helppp...