this thing about numbering gave me problem already in the past.
thanks to both of you, I have tried following your tutorail and guide but once I change the numbering of one paragraph, the numbering of all documents are messed up!!!

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I have solved in a more "manual way".
I select the heading I want to editi, end actually deleted manually the numbering, and typed manually the new numbering I want to assign. Word in auto create new correct numbering. It seems to work. At least I need to change few sections.
Thanks as always.