Text that should deviate from the creator's default needs to be marked accordingly, either by selecting the text & using Tools> Language to specify the Language, or preferably by applying a Style which includes the appropriate Language attribute.That default applies only to new documents created using that installation of the software. The Language specified in Tools> Language detrermines the default language for that user in that installation of Office.Language is a formatting attribute in Office documents.
A few points offered for clarification :-)
