Bars per line

There's Format > Add/remove system breaks, which maks sure that not more than X measures are in any one system.
Depending on various other settings the the systems' content it might be less thoug

Just add a system break every 4th bar by clicking in the bar (not on the bar line) and pressing [Return]. Of course, if the bars are too long for four of them to fit in a single system you will need to do something to make them fit, like changing the page size or reducing the margins or changing the scaling.