HI
I am Dave, I will help you with this.
Usually Windows gets the time form an Internet server, and that would fix the date and time, when you connect to the Internet.
Without being able to access settings, it would be hard to fix the time, can you open the old Control Panel, not the Settings app?
You mention you can fix this in school, is that PC provided by your school and if so, do they have administrative control on that PC?