Again, Why does Yahoo mail not recall my log in info every time even though I do everything right?

Try this : Next time you insert your password to enter mail, look for a small box below where you can check it. It says something like "do not ask me to identify myself".

However, when you use the Cleaning program to remove cookies..etc, you will be asked to insert password.

Furthermore, when signing out of Yahoo mail, do not exit, just click on the X in red top right of the page. But this way, someone else could get in and read your mails. So it's a bit difficult to decide what to do actually.