Unpredictable behaviour from MuseScore
For Marc Sabatella: This is an amendment to a very old thread (interrupted by heart attack). MuseScore had been closing without prompting me to 'Save' and Saved files were not saving. There were also problems with text boxes. I had promised to provide a sample file. I did produce a sample which exhibited the problems faced but this eventually began to operate normally. The program is functioning normally overall now, too.
I had been using MuseScore for several years previously (and since) and my methods had not changed. Indeed, the ease of use of the program had always been its biggest appeal.