why is my word document being saved with an extension .docx?
Perhaps because you have Word 2007, for which that is the default? Note that it
isn't just a different extension, it's a completely different file format.
If you want to use the .doc format for specific documents, such as for exchange
with people who have older versions of Word, click the Office button and choose
Save As > Word 97-2003 Document.
If you want to make the .doc format the default for saving, go to Office button
Word Options > Save and change the "Save files in this format" dropdown to
"Word 97-2003 Document (*.doc)".
