automatically add bars

I assume he means, he wants useScore to add measures (bar is often used as a synonym for measure). That is, when entering notes in the last measure of the piece MuseScore could in theory add another measures, thus eliminating the need to ever manually add measures. Finale has a mode where it does this. I personally found it more trouble than it was worth, as it was constantly adding extra measures long after I finished the piece, just because I was editing the last measure, so I spent more time deleting those autmatically added bars than I ever spend adding empty measures. S I got in the habit of turning the option off, and just starting each score out with way more measures than I really needed, deletng the extras when done. So I'd certainly want it to be off by default, and that's where I'd leave it. But I can see how others might still prefer to have the option.