Today I got the message from firefox that a new version was available,
and I clicked the button to upgrade to the new version.

Unfortunately, to my annoyance, when the browser restarted, it had
replaced my browser with the brazilian portuguese version (my windows
is in brazilian portuguese). Problem: It did NOT ask me if I wanted to
switch the browsers language. I prefer the english version for a
number of reasons: Ctrl-Enter adds .br at the end of the URL. I don't
want that.
Many shortcuts are different (and I couldn't find any documentation on
what they are in the portuguese version).
Installed Search engines in the search box are different, using
versions I dont like.

So, if it wanted to change language, it should at least ask. Now I
will have to uninstall, download the english version and re-install,
which means time wasted and (mozilla org's) bandwidth wasted.