How do I make my old email to the newer version (without deleting anything)?

I have an old email and a new one.
How do I make my old email to the newer version (without deleting anything)?
I am guessing here since your question is not entirely clear to me...If you are referring to MAIL CLASSIC and ALL NEW MAIL you will find those at the top of your email page...whichever one you are in...clicking on what is at the top of your present email page will put you back into the other..you will not lose anything and nothing will be deleted...hope this helps.
Reply:Do you mean you are currently using Yahoo mail classic and you wish to switch to the New Yahoo Mail? If so look for the link in the upper right corner of mail classic that says something like "switch to the new yahoo mail".