If you are creating a page with OptimizePress but are finding that different pages are showing in your menus when you are logged in VS when you are logged out of your site - this is most likely because you have a third-party plugin such as WishlistMember protecting these pages.
Wordpress will automatically default to show all non-protected pages from your menu if no unprotected pages are available to show. We advise where possible including at least one non-protected page in your menu to ensure this does not happen.
This is the intended Wordpress behaviour and fallback for secured pages/navigation menus and not something we can change
Alternatively inside your Membership plugin, check if there is an option to "show protected pages" or "do not hide protected pages" and this should ensure pages are still available in Wordpress menus and other Wordpress generated sections.