Yahoo email login issues ?

Up until about a week ago, whenever me or my wife would go to sign into our Yahoo mail, all we had to do was type the first letter of our user name and both of our accounts would show up - if I clicked on mine, the password would be there and the same for her. Now Yahoo won't remember usernames or passwords - I've gone into my tools and did pretty much everything to get it to remember our user names and passwords, but no luck - we still have to enter them manually. Did anti-virus scans, system restores, still no luck - no problem with other sites we go to - Facebook, etc, even my Comcast account remembers everything, it's just the Yahoo log in that is the problem. Any ideas ?