Hi,
using Menu/Desktop/Display settings/
and then
selecting «switch off desktop display and use external display»,
switches off the laptop display and switches on the external display asexpected.
BUT there, the «Save» key stays greyed and not active, as well as the other keys (i.e. «Apply»,«Cancel», and the check boxes).
I cannot save the new configuration.
After a few seconds (timeout is off), back to the laptop display.
I goggled around to find any workaround without success.
One thing although: a file «lxrandr.something.desktop» happens to be created in the directory /root/.config/autostart/
clicking on that file switches to the external display in a permanent way.
It happened some times, but I could not reproduce it systematicaly.
Thanks for any help.
Charlie