MS Word documents changing to .cpio files and then to .zip files
When a document opens with the wrong app the first thing to do is see what macOS thinks should happen.


In Finder find a document
Right click on it and choose Get Info
Look at what Open with... shows 
If it is the wrong application alter it to be the correct one e.f. Word in this case. You might want to Change all as well. 


If it is the correct app then more investigation needs to be done.