Hi there! My name is***** am a computer professional with over 15 years of experience with both Mac and Windows computers, software, phones, tablets, e-readers, and printers. It would be my pleasure to assist you with this.
Please login to www.yahoo.com using the info for the account that you are having trouble with. Click on the icon or photo with your name under it (in upper right hand corner). Next click on ACCOUNT MANAGER. On the next page that appears please click ACCOUNT SECURITY. Please scroll down and turn on "ALLOW APPS THAT USE LESS SECURE SIGN-IN", then check to see if you are able to add the account. Please let me know the results. Thank you!