If you want to change your password navigate to your PROFILE page and enter a new password in the PASSWORD section. You will be then prompted to enter your existing password.
Changing your password will cause all of your existing User Sessions to be revoked.
Reset Your Password
To reset your password use the FORGOTTEN YOUR PASSWORD? link at the bottom of the login form. You will be sent an email with a reset link in it in which you can follow the instructions to enter a new password.