Go to tools...options...searching

Check the box for 'show license warning'

Do a search for something copyrighted and try to download it

A box will appear asking you if you wish to download it, even though there is no license with it

Check 'always use this answer' and select 'no'

Hope this helps

P.S. Do you have any idea what your kids ARE downloading? You may find them disappointed if you apply these restrictions.