Design structures are important because they enable you to edit the default page styles in one place and have them applied to all pages (from the same design structure) at once. Having a common design structure allows you to edit and update content which is shared between multiple pages such as the header, footer, and sidebar only once.
To select or change the design structure, navigate to the Page Settings by clicking the Gear icon and choosing Page Settings from the drop-down menu. The Page settings editor is divided into two panels: the first one being the list of all pages on your website and the second one is where you can edit your page SEO and select a design structure for your page.
A simple visual distinction between pages with different design structures is the box before each page name, which is the same color for pages of the same design structure.
To change the design structure first select the page and then choose the design structure from the drop-down menu or, select “Add a new design structure” to create a new design structure.
Every time you create a new design structure, it will initially inherit all defaults from Design structure 1 including the header and footer content. You will need to override the existing styles in the new design structure.
Whenever you are making any changes in the header, footer or sidebar level you would need to publish all pages from that design structure (All pages that share the same header and footer) in order for the changes to be visible on the published pages. This is also true when you are making any changes in the Design editor that would affect the appearance of the other pages from the same design structure.
To publish your pages, select the Publish my website icon from the main bar. From the list of pages that appears in the dialog box, check all pages from the design structure you want to publish or simply all pages that have the same box color as the page you edited.
Click Publish once you have selected the pages.