No main page recognized

I cannot get the theme to recognize any page as my main page so that I can turn off sidebars. All pages are seen as single post pages. This makes turning on sidebars on main page and off on single post pages impossible. All pages are single post. I’m stuck. I did notice on editing at the bottom that you can turn off sidebars for that particular page, but you still have to have sidebar turned on on all pages for that option to work. When you are editing a single page, if you could have an option to turn on the sidebar after it has been turned off for single post pages, it might work. Am I the only one having this problem?