Getting rid of an unwanted line break in system

I have a composition that has a partial measure at the start and I wish it to have line breaks every four measures, except the first line, where the partial measure makes it five.

I was doing fine, until I added the third verse of lyrics, and when I added words to the last measure on the first line, it forced the last measure on that line to the next physical line, and stretched the measure across the line. There is no line break indicator a the top of the first line, only after the last measure that was pushed down.

I would like to return to the formatting of five measures on the first line, and four on every subsequent line.
How do I do that? I've been trying quite a few things, but nothing works. When I change the first five measures to be 5 to a line, it fixes the problem, except then a bar lower down exhibits the same behavior.

Thanks in advance.