If you don’t like the settings that are used in the default document or are always changing the settings then you can adjust the default document so it is setup the way you like it each time you start a new Word file.
The default settings are kept in a file called Normal.dotm for Office 2007 and up which is located in the C:\Users\username\AppData\Roaming\Microsoft\Templates. To change the settings, open the Normal.dotm file and then adjust the document to the way you like it. You can change the font, margins, add headers and footers and so on.
After you make the changes, save the file in the same directory as the Normal.dotm file but with a different name. Make sure you have the .dotm extension on the end. Then close Word and browse to that Templates folder and delete the Normal.dotm file. If you get a message that Word is still running then you can use Task Manager to kill the winword.exe process. After the original Normal.dotm file is deleted rename your new file to Normal.dot and then that will be used for the default Word template when you create a new blank document. If you want to go back to the original settings simply delete your new Normal.dot file and Word will create a new one when you open the program.