[bcrdukes]

Originally Posted by Presto

I usually just go the lazy route and take the entire contents of the original folder located in:
c: \users\yourusername\appdata\roaming\mozilla\firefo x\profiles\something.default

and copy it to:
c: \users\newusername\appdata\roaming\mozilla\firefox \profiles\somethingelse.default.

This.

(Worked for me.)