Word 2016 inserted RevNum field will not auto-update

I inserted the document revision from Insert->Quick Parts->Field->RevNum into my document.

It never updates the number unless I use F9 after highlighting it. This occurs for all fields including current Date+Time and last save time.

How do I set the fields to auto-update when I save the document so I can see what was saved? I found the option to update when opening, and the one for updating when printing. But how will I know which document revision to tell people about when I save when I then have to re-open it to get the revision?