Sitebuilder Plus: Password Protect Pages
Sites that do not use Master Templates will always have the password field available on every page. However newer sites that were created with SiteBuilder Plus and include the Master Templates, have a feature where this can be turned on or off. If you need to set a password for a page, but don't see the option, click the "Background, Links, Footer" tab, and then you will see a button that says "Set for this page". After selecting that button, then go back to the "Advance Settings" tab, and it will show the password field.