Hi,
I found the solution and it was related to AVAST AV.
I don't know why but it appears that the directory used by Calibre was set up during the night (certainly a software update) in a restricted area for JPEG
.
What I finally do is to authorize Calibre to this area (After I installed the latest release of AVAST without silent mode, it raised the points).
Now everything is working fine and and I can also modify the author with the associated directory change.
Thanks for your great job
Brgds