I have a new computer and need to know how to access my old firefox History files?

Read https://support.mozilla.org/en-US/questions/1176169 use '''about:profiles''' to get the current profile folder and that will give you an idea of where the old one is if you can access it. Backup the current history Then copy the old file to the new profile,

There's a Sync functionality to help with this: * [[Back up and transfer your Firefox data to a new device]]