Heading Style Update in numbered list not sticking

[Lin]

I have a document which includes numbered styles. Style 'Heading 3'
iincludes numbers. The lines in this style are wrapping with a hanging
indentation of .35". I would like that to be a hanging indent of .5". I go
to change style, make the change under Paragraph, Hanging Indent, and click
'ok'. The style reverts.
I made the style change in Numbering. No luck. I have tried clicking
'update template' and 'automatically update' before clicking 'OK' - that
didn't help.

I went to Tools - Templates and Add Ins, and turned on 'Automatically Update
Document Styles', (it shows a template of normal.dot) and made the change
again. Still a no-go.
I am very frustrated. How can I get this style change to stick?

 

[Suzanne S. Barnhill]

FWIW, the change must be made in Format | Numbering, not Format | Paragraph
(from Format | Style).