How do i keep user data seperate when the data is being processed in the same sheet

[rafae]

Ssheet: https://docs.google.com/spreadsheets/d/1Y5ssAERX3qGwmXjnlLfCcYV47UQE4F1v_P05TZ7E0vg/edit?usp=sharing

Appsheet: https://www.appsheet.com/start/9ab04f03-cf30-4edf-abd1-9c1c1a90b0dc 

I am making an app which makes it easier for students to choose courses for their next semester. One function is that the student enters their course code on the app. The data is sent to sheets where it is processed into a timetable. The timetable is then shown on the app.

The issue I'm having is that the data entered by students gets mixed up. So if student A enters 3 courses and student B enters 2 courses, both of them will end up with timetable for all 5 courses. How do i keep users data seperate from one another?

Please note that I am very new to appsheets and barely have an idea what I'm doing

[1minManager]

You need to use UserEmail() to detect the logged in user, or get the user to pick their name off a list

[dbaum]

SUMMARY TIP: User permissions, roles, and settings - Google Cloud Community