I recently installed Electrum 3.3.8 from electrum.org and have verified the download.
B. I briefly installed Electrum when playing around with Bitcoin back in 2014 and it's somehow defaulted to those setup details (although none of my regular passwords are working),
So.. when exactly did you install electrum?
Recently.. or 5 years ago ?
A. I've fallen victim to some kind of malware scam.
This can not be the case. At least not regarding some fake electrum malware.
Well.. at least if this statement is true:
I recently installed Electrum 3.3.8 from electrum.org and have verified the download.