Thank you for your suggestions. I finally had a chance to get back to the problem with my files.
Have converted them to .pdf with Adobe Reader. Thank you for this tip! If I go to "All Documents" in Kingsoft Office, I can open and read the files. Great!
Now I have another problem....
The file path in Kingsoft Office is:
/storage/emulator/0/KingsoftOffice/file
My problem still is that I can't edit the files. This is probably the wrong path for that purpose. Also, I still have some of the nonworking .docx and .txt files there which I can't see how to delete.
If you have more suggestions with editing & deleting files file in Kingsoft, I will appreciate it very, very much!!