I need to change the default global width to '0' since my polylines are showing up 2" thick, but can't seem to find the default setting for this. I assumed it would be under format but am not finding it.
Both of the above commands are correct, and will do what you want them to do. one point to note though is, if you have already createed your polylines, and you want them to be a narrower width, you can change them in the proporties box.
press ctrl + 1 to activate the proporties box, select the polyline(s) you need to change and then select global width on the proporties box and type in your desired global width.