How do I change my sign in name?

You'll have to create a new account. The current one you have now can't be changed because of security reasons. Go do that here: https://edit.yahoo.com/registration? You'll be able to still use your current password this way.

Conversely, you can create an extra email address under your current account by going here: http://edit.yahoo.com/config/list_alias

You will need to make a new account. You will be able to use the same password though.

If the name you want to change is included in your account ID, you cannot change it. You will have to cancel the account and open a new one with the new information and password.

If not, you can go to, then click on: Options / mail options / account information; and change the info there.