For the messenger:
Go to your yahoo messenger friends list. Click on messenger, then click on %26quot;my contact details%26quot;, underneath the box in which you could enter your first, last and middle name is a box that says nickname. Enter your new nick, save it and you're done.
If users already added you to their messenger list and/or address book, your old name setting will continue to get displayed for them. If you want those users to see your new name also, ask them to remove you from their messenger list and/or address book and add you back with your new info.
You had me confused there for a little while because your question was placed in the mail category and the built-in messenger for New Yahoo Mail doesn't allow chatting in chatrooms...:-)
