I have been trying forever to:
1. modify my NORMAL.DOTM
OR
2. Use a different .DOTM file

specific changes margin size and paragraph features

If I edit the normal.dotm file the changes don't stick. When I reopen it, it is the same as original.
If I change the name to normal3.dotm, when I reopen it the changes are still there.

OK, so how to use a new normal? I have no clue!

word 2016
an answer to 1 or 2 or both would be appreciated.
thanks