How do we return to last "new" version or even classic yahoo?

What Yahoo mail are you using if you started you mail account with beta no you can't go back.But if you had the all new mail or classic mail it can be done I had the same problem and could not find a way to go back I got so pissed that I did a chat session with a yahoo mail customer service rep.And was told I can't go back well I told him that I thought that Yahoo was better than that so I.Then told him that if I can't go back then I think that it's time for me to say good bye to Yahoo.Then I was asked my security questions then I was asked to answer my security questions and the Yahoo mail customer service rep switched me back himself from beta mail to classic mail I only had to sign out of my Yahoo mail account while he was switching my account back