It was almost resolved, but not yet totally clear to me. My apologies to all respondents if I am a bit obtuse here.
What I would like to know is what is the correct starting procedure before and during the opening of a new file drawing, to set all permissions to "read and write", to safeguard against striking this obstacle and possibly (actually in the past) losing a drawing again.
I need to know Specifically:
1. Any and all places where full "read - write" permission need to be set before starting to draw.
2. What is a totally reliable way to prove the above is successful before spending hours or days on it? Can the file can be opened without the access warning. Is it ok just to start the drawing, close down and open it from /home/drawings? If that opens, proceed with confidence?
When I opened my file manager again to check the changes, it had reverted to the blank settings below. Should I re-start my computer to "hold" the settings I select? Maybe this is a problem for the Linux Mint forums?
I did restart my computer, but the changed reverted to blank, as above.