Password Autosave - Yahoo Email Login

Every time I want to log-in to my Yahoo email account using CD I have to type in my full username and (long) password. On every other website where I need to log in using my username and password, CD automatically predicts it for me, but I have never been able to (or even been given the option) for CD to autosave or predict my details in Yahoo. I use many other sites with my “saved passwords” and they work fine. Why won’t this happen with my Yahoo account?