Your site has a default set of modules that appear under the main content of most pages. When creating a static page, news post, video post, or game you can elect to use the Default Modules on the additional modules tab (default setting), or you can modify them for that specific page.
If you prefer, You can edit the default settings globally by navigating to /admin > Configuration > Pages Configuration.
Select the page type that you want to modify & then add / edit / delete modules as needed. (not all page types are available at launch, but will be shortly)