Thank you very much for Execrable and Irvinewade!
Some of my problems are solved thanks to you:
I was able to update the system
I could change the screen resolution
Concerning Geary: the returned message asks me to check the incoming server settings. I checked and rechecked but they are the ones I use on my computer (Linux) and my tablet (iOS). I wonder if this is not coming from the ISP itself because I get from time to time a message about a “certificate” problem…
Concerning the memory card, it’s the one I use on my Android phone (under a French version of Lineage: /e/ or e.OS). Maybe it is not formatted in a format compatible with PureOS ?
Could I connect a USB key directly to the Librem, in order to retrieve files ?
Concerning the French language : Yes, I have chosen the French language from the beginning.
On the other hand, I don’t see any application to use the camera to take pictures ?
Is there one?
Thanks again for your help!