hi, is this a question about desktop or mobile firefox - in case it's the former, perhaps you should use different user accounts for different users accessing the device...

How do I share Firefox between people on a computer?

Thank you, It is desktop. I'm good with sharing my computer but would like to know what is being searched/history by the other user which it does not belong to. They are intentionally deleting & not leaving a trace by changing the settings which I have ask them to not.

Example, At work I'm not allowed to use computer for personal use. I follow that rule & haven't tried. So how can a computer be setup so a user can't do whatever they want? Or at least their use be monitored.

Create a separate user account on your computer for others to use.

As to where they are going, there is software available to record that the computer is doing. Most such software is listed under child protection.

You can lock specific settings, but you can't prevent others from deleting history via "Clear Recent History" or otherwise like in the History Manager. If your router can keep a log then you can consider to enable that feature.

• https://support.mozilla.org/en-US/kb/customizing-firefox-using-autoconfig