How do i change my registered name from Leah Jossannee Welborn to Leah Jossannee Ligad.?

I already change my profile but everytime i sent an email, the old name still appears. I want to change it from Welborn to Ligad. Need your help.How do i change my registered name from Leah Jossannee Welborn to Leah Jossannee Ligad.?
How to change how your name appears on your outgoing email:



Adjusting the ';From'; field changes how your name appears in other peoples' incoming mail.



You can also adjust the email address they'll send a message to when they click ';Reply.';



Here's how to do it:



Click Options in the upper-right corner of your Mail page and select Mail Options.



In the box on the left, click Yahoo! Mail.



Click 鈥楪eneral Preferences鈥?



In the ';From name:'; box, enter your name how you'd like it to appear in the ';From:'; line of your outgoing messages.



Example: ';Jane Doe';, This is the name people will see in their Inboxes for messages from you.



You can leave the ';Reply to:'; field blank, so your Yahoo! Mail address is automatically the return address when others reply to you.



Or, you can specify a different return address by entering it after ';Reply to:';.



Click Save to put your new settings into effect.



Note: The ';From name'; field can't contain special characters like the ';@'; symbol. And, the address in ';Reply to:'; can't exceed 40 characters.



http://help.yahoo.com/l/us/yahoo/mail/or鈥?/a>