Mail display name

Hi,

Some people who receive emails from me see a display name that I had set about five years ago, despite the fact that I have changed this in the mail preferences section. My email was created with Yahoo, and so I have also changed the display name on my Yahoo account, and I have checked that it has changed on all of the devices I use, which are my Macbook Air, my iPad 2 (which I believe I set my first display name on) and my android phone.

Thanks

Anna