Contents in courses list is different between Android and PC web

When I select courses on Khan Academy using my Android smartphone, I find that there are 10 courses available to choose from in the Reading & Language Arts category. However, when I access Khan Academy on my PC, I am only able to see 3 courses in the same category, and it appears that all the courses I had previously selected have disappeared.

How can I view and select all the courses on my PC as I can on my smartphone?