Go to Theme Options -> Page to manage the settings for the default page layout and sidebar.
Page display settings
The similar way you do for single posts, you can edit these options for each page separately.
Watch an example in this short video:
Authors page template
The authors page is a special template which you can use to display all your website users (authors). As described in the image below, you just need to select the Authors template.
Blank page template
The blank page is a special template which you can use to create full-width custom pages. For instance, if you need a page for special shortcodes, page builder elements, pricing tables, or custom landing pages. As described in the image below, you just need to select the Blank template. Optionally, you also have the set of display options to remove the header, footer and page title.