To change your password:
Profile --> Account Settings
Type new password in "Choose Password"
and you'll need to verify that change by typing in your old password where it says "Current Password."
To retrieve your old password, your e-mail associated with your account must be up-to-date and accessible by you. If you try to log in to E and fail, there will be a link that says "Forgot your password," which you can click to get a password reminder sent to the e-mail associated with your Elliquiy account.