This is most likely because you have Part Markers placed in the song - these are the green or blue boxes around the bar number. These are used for song flow, say if you have a verse that's 14 bars you would add a part marker at bar 15 - a new line is added because it's assumed the new song section should be visually separate from the previous one. You can learn about Part Markers here:


Part markers are like pressing enter when writing an email.
Sometimes you
might want to create
a new
line.
That's part of what part markers do, as well as controlling drum fills and substyle changes.

You can click on the blue or green boxes to take them out if you want or if you inadvertently placed the part marker in the first place. If you want to disable the new line, please go to Options > Preferences > Display, then uncheck New Line For Every Section.


I work here