Blog Page Settings: In "Customizer" you can select the layout of your Blog Page and the choose location of the Sidebar.
Customizing => Blog Page Settings:
404 page Settings: In order to change 404 page Settings please go to "Cuztomizing" => "404 Page Settings".
For example, this page can looks like screenshot below:
The Customization menu is intuitively understandable and very easy. It provides you flexible control of the appearance and behavior of the whole theme.
