After seeing the message about moving headers in
Thunderbird, I installed the add on out of curiosity.
It appears there are some fields you can move and
some you can't; If you want to subject line after the from line, move the
subject line, which you can move and not the from line, which you can't.
The addon reports that you have moved the from line but it hasn't moved.
You'll have to experiment to see which fields you can actually move and which
you can't.