Change the Default file format from docx to doc while saving in Word 2010
In Word 2010 , when you save a document it saves by default in docx format .
One can easily change this in Office 2010 from docx to doc format .
To change the default file format to be used while saving , follow the below steps .
1. Click File Menu – > Options
This should opne up a dialog window ( Word Options ) .
2. In the save tab , select the option “Word Document (*.doc) in the save files in this format and click ok button .
Now , when you save the file , it should be saved in the .doc format 
