I have great respect for the Lynda series. However, they tend to believe Microsoft.
How to create numbered headings or outline numbering in Ribbon Versions of Word by Shauna Kelly

If you do not use this method and you do much editing in your document your numbering is likely to break or become spaghetti numbering (technical term). Since you mentioned Heading 1, you may have done this but not necessarily set up your styles themselves, just the numbering.