The demo show on every page I set up as home page

Hi there, I really have an annoying problem. The demo homepage shows no matter which page I select to be the home page. For example, I designed a page called "photography", and I want to make it the homepage. so I go to settings-reading-homepage-select "photography" as the new homepage, then refresh, I still see the demo homepage. Why? Can anyone help me out? It is urgent. I am finding a job. and I Need my website finish. Many thanks!