This is what I found:
Format>Paragraph>Indents and Spacing tab.

Alignment shows, “Left."
Outline level shows, “Body text."


Indentation Left and Right: Both show, “0cm”
Special shows, “None.”
BY box: Shows nothing.
Spacing before and after: Both show, “o pt.”
Line spacing: Shows, “Single.”
At box: Shows nothing.

Nothing changes.

The problem has been solved by someone on a forum called "Computer Active" who advised me as follows.

With Word closed, I would rename the Normal.dot template to get a comparison with new documents.

If you press the Windows + R keys together, in the Open: field, type, or copy/paste the following blue text: %userprofile%\Application Data\Microsoft\Templates > OK or press the Enter key.

Look for the Template named Normal > Right click > Rename to > Normal.old

Restart Word, and a new Normal Template will be created for you to try a few sentences and paragraphs created by the Enter key.