If a student is enrolled in more than one section, the student will see a section name at the top of their page upon logging in.
You can see that this test student has "Girls Who Code" at the top of her page. That means that the student can access the course available for that section without doing anything.
If the students needs to access the course from the other section, they should click on "Girls Who Code" (whatever the name of their section is) to pull up this page. Here the student can then click the other section. This will allow the student to view the correct course that the other section is enrolled in.
If your student is experiencing a problem, it may be because they are accessing the wrong section. If they follow the instructions above, this should help fix the problem. Please email your Account Manager (if Pro) or firstname.lastname@example.org if this doesn't resolve your issue.