Your password is a way of protecting your account. It is a group of letters, numbers, and or words. You enter it along with your user name each time you sign in. You should not give your password to...
When you sign into piczo, look at the top right of your window. It should say "Account". Click there and you will have a list of options, including changing your password.
I believe that you are asking why some sites passwords and/or usernames are not remembered. In such a case it is likely that either you cleared some type of history, data, etc, or possibly updated a...