Many thanks again! When I originally view my site, there is the navigation arrow on the right side, and can scroll continuously through the whole site. But if a click is made to enter a post, or if a tab is selected, the arrow is only functional within its own tab, and a return to the Front page (which only has 4 images) shows no arrow at all unless you re- log-in. This is different than the demo here — is there a way to fix it?
Open Developer Tools (F12 on most browsers or Cmd+alt+I on Mac) and click the console tab. See if you have any JavaScript errors, especially on pages different than the front page. See by which scripts the errors are generated and if they belong to a plugin try disabling that plugin and see if it still behaves like this.