I can't get yahoo as my mac mail account despite following the advice re: system preferences -adding the account under system preferences or as add another account

Hi.

I can't get yahoo mail to work as my Mac mail account. I have followed all the steps re system preferences, adding a yahoo account, trying to do it manually under add another account too. My login details for yahoo are correct but still mac won't verify the yahoo mail account. My husband changed the Mac to link it with my apple ID recently and thats when the problem started