It sounds like maybe you are referring to Private Browsing mode. That would allow you to use your bank and then all of the data from your session will be deleted when you close Private Browsing. See Private Browsing - Use Firefox without saving history for more information.

I'd also recommending reviewing the Common Myths about Private Browsing page to clear up some common misunderstandings when it comes to Private Browsing.

Hope this helps.

Thank you for your help, I will tell you my problem, I just bought a new dell laptop with windows 10 installed, I had an HP with windows 7 pro, but it was getting old. On my old laptop after a visit to my bank I would go to history, and would clear my history, but in order not to loose my bank card number when I next went on line to do my banking, I would un check the cookies box and that would keep my bank card number for next time I logged into my banking. Now that I have windows 10 , I have been told not to do that any more, so I wondered if there was a way I could save having to re-enter my bank card number . Apparently , this private browsing would do that ? but it doesn't seem to be safe, is there any way to be safe when doing my banking on line ?

PB m9ode doesn't keep cookies at all (cookies are purged when you close all PB mode windows), so Private Browsing mode isn't what you need if you want to keep some cookies.

Can't you store this card number as form data or possibly in the Password Manager ?

In the Lockwise Password Manager you can create a new login and store this data more safely if you use a master password than via a cookie.

The clarify, clearing your history has little to no security benefit. All clearing the history does is remove it from the list of websites that you visited recently.

As a side note, you could take advantage of the Multi-Account Containers feature in Firefox and open your banking in a "Bank" container. That would keep it separate from the reset of the websites that you visit.

My general recommendation to you though is to get an anti-virus program, even if it's something free like Avast or AVG. That will help reduce the likelihood that your computer would get a virus, which will help keep you safe.

I don't know how to install multi account containers , I looked into it a bit and it frightened me as it changed things on my computer, where can I go to learn what to do to get an account container

The Multi-Account Containers feature is an add-on that you can download from the Firefox add-ons website.

They also have a nice video that you can watch for a quick overview of the feature.