Once you realize that "Customize" means "Change Password", there isn't a problem. When you are logged in, click Customize and it brings up the page shown above.
Just put your old password in the "Password" box, enter a new password in the "New Password" box, and type it once more in the "Confirm Password" box. Press submit, and if the "New" and "Confirmed" passwords matched, your password will be changed.
If you've forgotten your password you can either email a password request to Loki or you can click the "Forgot your password?" text which appears after an unsuccessful login attempt.
Then, enter the email address you originally gave Loki and a link will be sent to you. Click on that link, enter and confirm a new password and you're good to go.