Hi @BarbaraBesal ...
Are you, by chance, also a Canvas administrator? (I couldn't really tell based on your question, but it almost sounds like you are?) I am a Canvas admin, and I am only enrolled in about 20-25 courses, and I also do not have the drop-down menu. That's because I have access to well over 100 courses as a Canvas administrator. So, I'm not sure if you were recently added as a Canvas admin or if you've been an admin for a while now, but that's how this part of Canvas works (by design) based on the Guide you linked to. I'd be curious to know what kind of role you currently have at your school. Looking forward to hearing back from you soon!