A family of Microsoft word processing software products for creating web, email, and print documents.
In Word for Windows, click File > Options > Save. What has been selected for Save files in this format? This setting controls the default file format.
On the other hand, if you choose to save an existing document under a new name, using the Save As dialog box (press F12 or Fn+F12), Word suggests the current file format (which must then be changed manually).