The controls will not automatically turn off. Sometimes kids get smart and log on the router to turn controls off. This happened to other parents too. Maybe your router password is easily guessable (similar to your other passwords?), maybe you wrote down your password somewhere, maybe the kids are spying on you.
Next time you do a change, log out then log right back in. See if the controls remain intact.
BTW, you don’t need to use MAC address blocking to “pause” the Internet. You can use the “Pause” button on the Access Control page. Click on the button to add time to pause. Internet will resume after the pause time expires.
Or, you can double click on the “Pause” button to pause indefinitely. In this case, Internet will not resume automatically. You’ll need to log in again to manually resume.
“Pause” only pauses devices under parental control. Devices under profiles where parental control is turned off will not be affected.