This is how I do that or more preciously how I move my Firefox settings, bookmarks and add ons from one computer to another. I like this because it also keeps all the favicons as well.
First make sure your computer is set to see hidden files and folders. Depending on what version of windows you're using the files may be in a slightly different place. This is windows 7. And I always make sure the firefox versions are the same.
Open My Computer and go to: C:-Users-The user name, in my case it's P-AppData-Roaming-Mozilla-Firefox-Profiles- xxxxxxx.default
Notice the file name .default will be different on every install. That should be all the stuff you need in there.
With that file open I select organize, select all and copy and paste the files into a folder.
Next is to move that folder over to where you want to use it, go through the steps to the destination file and with that file open paste the files into that folder. You will get a warning, I don't remember exactly, do you want to overwrite these files, something like that. Anyway clik yes and Ok and you should be good to go.
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