Thank you for your reply. Yes I had done the changes in ‘Customizer' just as the video explains.
This had been my assumption that all saved changes would be ‘global' to my site. However it appears not to be. As mentioned above, the home page is fine, just as I designed it, but clicking on any of the navigation bar links throws it back to the unchanged format.
Please take a look http://oilisenergy.com/