Logging in to Admin area in version 1.4.8b

I've kept version 1.4.8b because my business is small and the work involved in upgrading wasn't worth it.

For the first five years, I was able to login to the Admin area and then open and work on dozens of pages at once. Now, OpenCart is demanding that I login over and over again. Since my installation of OpenCart hasn't changed in a couple years, I assume this must be because of a browser upgrade. Is there anything I can do to login and work on multiple pages, like I used to? Thanks.

Oh, sometimes I get an "Invalid Token Sesson" error, but not always. Even if I don't get that, I find myself having to log in over and over, and I can't have more than a few pages open.

I did a search for this problem, but your search system kept giving me errors.

I'm using the very latest version of OpenCart and firefox and I have the same issue because the tokens are not carried over to new pages.
My workaround is to right-click and open in a new tab/page from within an OpenCart browser page. This way I get the same token for all web pages opened.
Every time you log in you get a new token and this invalidates all your other open pages.