format of page after inserting page break

My interest is in creating piano parts with convenient page turns. I have included a work in progress copy of the second movement of the second Faure piano quintet. My general question is, how best to insert page breaks? For example, in examining page 4, I wanted to put a page break after bar 90 (it used to have a few more bars than this). What I got was a page 4 where bar 90 spanned the entire line. I suppose I could fix up page 4 by putting in my own line breaks, but I wonder if there is a better way.
At other times I have wanted to increase the number of bars in a page. Suppose I want one more bar. If I go to the next page and insert a page break after the first bar, I get a page with just that bar. What should I do instead?