Answer:
The way I do it is go to File > Save As
Find a location to save the file, name it, and then in the drop down menu find the option that says ".doc"
This should make it compatible with older versions that don't support ".docx"
Also if you want to check the formating to see if it will work, there should be an option for that too somewhere in the menus at the top of the program.
Explanation:
