Is there any way of doing this so the headings and sub-sections are numbered automatically? it seems I have to designate text as heading level 1, 2 etc, [then manually change the font and color so it's not blue 20 point - but that's on old issue], then click the multi-level list, then indent as required. Surely the TOC should be easier than this. Why don't the other headings get numbers automatically?
The TOC is based on styles that you can choose. By default, headings 1-3 and outline levels 1-3 are included in a TOC.
The numbering is normally done using the headings, but you could use any styles. Luc pointed out a simple way of associating automatic numbering with heading levels.

You can find that under the MultiLevel List button (not the list button).
You can set this up however you want. Here is my pdf with multiple links on how to do this: https://www.addbalance.com/usersguide/AutomaticNumbering.pdf
Styles can be modified. You do not want to go through your document and change the formatting of the headings. You want to modify the styles. If you are not understanding and using styles you are definitely doing things the hard way.
It would be possible to have numbering apply only to the TOC without it applying to headings in your text. It would be unusual to do so, though.