My novel's body text is formatted w/no tabs, indent .25 after single line. And each chapter is centered Heading 1.

I have to send it to an editor, but in 3 chunks. I'd like to keep all that formatting once it comes back (387 pages of it).

How do I cut and paste all the parts and keep its formatting?

Ray

Did you try Copy and Paste?

What happened that you did not like?

Work with copies of documents until you get it the way you want.

Do your formatting in the future using Styles. You made a start with that using the Heading 1 style.
Understanding Styles in Microsoft Word

I'm selecting all, copy & paste into new blank docx. None of my formatting appears in the new docx.

I've spent hours formatting the original, don't want to redo it after editor's cut.