Try to access your Yahoo account security page through a web browser on your computer. When you get there, enter your Yahoo email address and click “Next.” On the next screen, you will be asked to enter a password.
Since you do not know the password, click on the link I forgot my password under the login button, and you will be taken to the account recovery screen.
If a recovery email address is added to your account, you can use it to reset your password. If this does not work, you can answer your security questions, and this will allow you to reset your password.
Therefore, simply by answering security questions, you can reset the password for your Yahoo email account. It even works for resetting your Yahoo email password when the phone number changes.