The logs should be not too hard to find, as they are in the "Logs" folder.
I do see Z2fxdemo.log, which contains only data of the current Zorro run. But, I can't find data about previous trades anywhere. Is that data lost forever?
Oh, sh*
I now see demotrades.csv, and also understand why it's so short. While I was testing beta versions, at some point I made a clean install, and didn't save the log file. So, I shot myself in the foot. Well, OK, I'll be more careful next time. Sorry for the noise.
