If you want to add your signature in you yahoo email account.
Sign in to your yahoo email account
Go to the setting option
Click on account
Here click on mail address
A box will appear for you
Click on "Append a signature to the emails you send option"
Here you can add your signature
Now click on save.
Your signature has been successfully created.
Related link
how to change my password
Add your alternate email address
Yahoo contact number 0800 098 8424
If you are still facing in adding your signature and other yahoo email issues then you can contact with us on our yahoo contact number 0800 098 8424.
For more info you can check this link yahoo email account support contact number
