Parental controls useless with chrome and firefox.

Putting on parental controls results in continuous popups from both browsers asking for access to secure websites. User cannot type unless they close the popup. As a result, they basically can't do anything with these pop ups - in chrome: Google Chrome Helper attempted to access these secure websites - then a bunch of website urls start loading up.

I've looked at other threads - didn't find a solution. There has to be a simple solution by now - but I haven't been able to find it. If you got a link to the solution - please post it. Imac in question is in high sierra.

Thanks.