Thank you! Problem solved.
When things are not good
and you want them smooth,
don't dismiss a reboot.
Sorry about that!
https://a3nm.net/blog/xrandr.html
Thanks.
I run that command but don't know how to use it to setup my second screen.
amuza@trisquel8:~$ xrandr
Screen 0: minimum 8 x 8, current 1366 x 768, maximum 32767 x 32767
eDP1 connected primary 1366x768+0+0 (normal left inverted right x axis y
axis) 277mm x 156mm
1366x768
You can try to set up the screen using xrandr.
Hello,
I have a laptop connected to a second screen. Both screens worked ok with
Trisquel 7. Now, with Trisquel 8, the second screen is not detected. How can
I fix it?