This is a great question guys! Our registered “Primary Sidebar” on WordPress is located underneath the content of a page or post. This is to bring the attention to photos in the centered content area.
If you would like to have a left or right sidebar, you might want to look at an easy solution like Conductor. Even the base solution of this plugin will allow you to have a left or right sidebar on your posts or pages. Better yet, you can use this plugin on a page by page or post by post basis too: https://conductorplugin.com