How to modify sidebars

I’m trying to modify the sidebars on Course pages to remove the default recent posts widgets etc. I’ve created a new empty sidebar in my theme, and when I apply it to the “Courses” page that Sensei has listed under “Course Archive Page – The page to use to display courses.” in the settings, the changes aren’t applied. Even if I change that page to a Full-width page in the theme options. Do I need to setup a specific page template?