Reader unable to save file after adding hi-lites and/or comments

Beginning on 10/23/18 Adobe Reader DC (Version 2019.008.2080 running on my Dell Desktop #19) ceased being able to save PDF files after modification in Reader (after  applying hi-lites and/or inserting comments).  Restarted my Dell Desktop #19 .   Then used Adobe program internal help menu to try to update the program (response = no update available). Then tried to `repair’ Reader using the internal help menu.  (The process completed with no error messages nor completion message). I have been running Acrobat Reader (and predecessors) on this device for at least 4 years without difficulties.   How else should I try to repair this new problem?