Dear people, my roommate would like to use my laptop as long as it is being repaired. For this I want to create a new user for him. Now my question is how can I make sure that he will definitely not be able to access my data even if he gets his own username. I saw that my programs were strangely visible and usable for him.
Set up an account without admin rights, then he can only access his own data and only the programs that have been installed for all accounts.
Of course, you can't give him the password for the admin account.
You probably chose to install programs for all users.