Most user settings can be changed in the User Control Panel, link at the upper left.
If you have forgotten your login password: while on the login screen, click on the "Forgot your password" link. Enter your username and registered email address and click enter.
A temporary random password will be sent to you by email to the address in your Profile. In the message containing the temporary password will be a link which MUST be clicked on to activate the temporary password.
After you are successfully logged in with the temporary password you can go to the User Control Panel, Profile and change the temporary password to anything you like. It will be necessary to activate this password as above.