I want my classic version email?

Answer 1

You can unlikely change the format of the website once it's been updated.

You can contact Yahoo email support
Contact link - https://au.help.yahoo.com/kb/account

https://io.help.yahoo.com/contact/index?...

Answer 2

It isn't possible to change it back. Starting January 31st, 2019, the classic version of Yahoo Mail that you’re using on your computer will no longer be available. To ensure continued access to your Yahoo Mail account, you will be automatically upgraded to the latest version of Yahoo Mail or Basic Mail, depending on the compatibility of your computer’s web browser.