1. Open Microsoft Word from the 'Office applications icon on the desktop
2. Click on the 'File' tab (top left)
3. Click 'Options'
4. Click 'Save'
5. Where it says 'Save files in this format' click inside the box immediately to the right
6. In the drop down list click on 'Word Document (*.docx)
7. It will say 'You are changing your default file format to Office Open XML......... Do you also want to change this setting for all other Microsoft applications....?' - Click YES
8. Close Word and try again