There is not an easy way to disable private browsing, nor to prevent users from deleting history accumulated in regular browsing. If you lock down Firefox with add-ons or style rules that hide menu items, a user can restart with add-ons disabled. Firefox also has a Profile Manager that would allow a user to create a new Firefox profile with default settings.

For those reasons, among others, I suggest you consider using a system-wide solution for monitoring and managing internet access on your system. For example, you could take a look at K9 Web Protection: http://www1.k9webprotection.com/

See this thread :

https://support.mozilla.org/en-US/questions/1220469

The recently launched "Enterprise" edition of Firefox 60 has management features that might help you. It is designed for companies rather than families, but it's a tool to consider.

I've never tried it myself, but you can create a "policies.json" file with contents like this to change how Firefox works:

{
  "policies": {
    "DisablePrivateBrowsing": true,
    "DisableForgetButton": true,
    "SanitizeOnShutdown": false
  }
}

See: Customize Firefox using policies.json

Also, other articles here: https://support.mozilla.org/products/firefox-enterprise/customization-firefox-enterprise-environment

Thank you for your reply, but that solution is way to complicated for me. I didn't get any of the instructions about firefox and policies and distribution. I'm baffled firefox doesn't allow you to controll the availability of these features.

Sincerely

danielsjoo said

Thank you for your reply, but that solution is way to complicated for me. I didn't get any of the instructions about firefox and policies and distribution. I'm baffled firefox doesn't allow you to controll the availability of these features.

Have you read this article :

https://support.mozilla.org/en-US/kb/block-and-unblock-websites-parental-controls-firef  ?

(see the other thread I mentioned ...... )

McCoy, yes I've read that other thread, and I've worked with filters and parental control. Thing is, as long as you can surf privately, it's not easy to see if the filters and controlls actually work, OR what kind of behavour my kids have online. I don't want them to (I'm not sayin they do!) try to find loopholes in the filters. If they know there's no way to be anonymous, that's a lot more effective, in my opinion.

danielsjoo said

Thank you for your reply, but that solution is way to complicated for me.

Sure, I'll point you back to my first reply: https://support.mozilla.org/questions/1229792#answer-1143650

-) Yeah, and I guess that's takes us full circle - it's simply not possible. Thanks for taking the time.