Is My Parents' Computer Secure?

Brad set up his parents' new Windows computer with bookmarks so they can easily visit their favorite websites. Is that secure? Leo says, unless someone else has physical access, it's secure. He's also had it set to go to sleep and require a password after 10 minutes of inactivity. Leo says that's a good idea. But Leo also recommends giving them a basic user account, not an administrator account. That way they can't install anything or give someone remote access, or even privilege escalation. Based on what Brad has laid out, their computer is pretty locked down.