Windows 8 Making parental controls permanent

I have a 15 year old son. He was on his laptop as an administrator but was accessing websites that were not allowed. I went in and added myself as an administrator and then changed his account to "standard user" so that I could then set the parental controls. Apparently, however, he was able to go in to the control panel and simply switch himself back to an administrator. Is there a way to make it so that he cannot change himself to an administrator? If not this is a serious flaw in the software, since most 15 year olds know the OS better than us older folks.

 

[kemical]

Here are a few web links to help. Also is the pc os installed under your sons name? If so, it might prove harder to keep him out.

How to use parental controls in Windows 8 | How To - CNET

How to block porn completely from your computer | eHow.com

Set up Parental Controls