I would like to force the printed version to start a new line after, say, bar 8 or 12.
How can I tell Noteworthy to go to new printed line at a specific point rather than letting NW make the decision where to line-break?
Ah.
Select a bar line, right click => properties => system break
Having done this you will also want to use this tip:
https://forum.noteworthycomposer.com/?topic=2311