Conversion to .docx isn't working properly

Hoping there’s a quick fix for this! I’ve tried compiling a novel to .docx first using 5.06" x 7.81" page settings and then just A4, and both times the pages are the right size on Word but all titles and text cross over the page as if it needs two full pages. I’ve attached a screenshot so you can see what I mean. It doesn’t seem to matter what font size, margins or page layout I set up in Scivener - it just keeps doing this when I open the file in Word.

Can anyone help?