Thanks for responding so quickly, but no, that’s not quite what my problem is about.
I know that “Word documents come with the default language set,” as you said.
In my case, the default language is & always has been set to English (U.S.)
My problems occurs while working on a new or existing document of my own making (not imported from elsewhere,) so they are, without exception, in my default language.
If I then enter a Hispanic name or French cooking term, for example… the entire document’s language-default automatically switches to either Spanish or French.
I could see if Word’s auto-correct function merely highlighted those names/words as not being recognized, or if the language-switching occurred in documents originally composed on a different computer… but neither is the case.