Hi there and welcome Al
The section breaks are correct, but the headings will not stay in place. The reason is as you add more text above it, it needs to push the text down the page in order to make room for it. This is why you are having the heading move down the page.
The only way to stop this would be to stop adding text above the heading as then it would not need the room to push down all content below it.
Does this help explain it to you?