Thank you for your comments.
First of all, you are correct: LO version is 6.3.5.2.
I understand I need to put Heading 1 in the text area. The problem is I’m writing a church book and the normal custom is to put the chapter heading at the very top – the Header.
I have tried to modify the header in the master: Insert>Field>More fields…. as you suggested. This did not work. But may I ask: how to modify the master since the Sidebar doesn’t exist in master document?
To clarify: three main bodies in my book (front matter, body, and back matter)
• one column preface (12 pages including front cover, title page, introduction… and TOC) using Roman numerals i to xii;
• main body: two column starting on page 13 but I noticed in the master document it shows ‘13’ (Arabic) and not ‘1’ as I wanted.
Clearly I have not done the setup properly?