I just upgraded from Win 7 to Windows 10 July 2016 and find I cannot open docx attachments sent to me in Windows Live Mail. I now must first save the file to a folder, start Microsoft Word and then open the file with Word to view it. I find this an unacceptable degradation of functionality from Win 7.

I checked to see what application was associated with the docx file extension and there was none. I only saw a plus sign. Clicking the plus sign the only choice was to go to the app store and get something. Word was not shown as a choice. I have Microsoft office 2000 and Word has been upgraded with the file converter from the Microsoft web site.

How can I override Windows 10 and associate Microsoft word with the docx extension to restore Win 7 functionality?