Ubuntu – Refresh display settings – using xrandr / Laptop screen off, external screen on

After setting the screen via GUI

In the line (in the output of xrandr after you set the screen via GUI):

HDMI1 connected 1920x1080+1600+0 (normal left inverted right x axis y axis) 509mm x 286mm

the position of the second screen (HDMI1) is defined top-allined, at he the right of your main screen (LVDS1): 1920x1080+1600+0, as explained here.

Before setting the screen via GUI

The definition of the position of your right screen seems to be missing for some reason.

I am not sure what causes the behaviour, might be a minor incompatibility, but it should be fixed with the command:

xrandr --output HDMI1 --pos 1600x0

Which will position the second screen at the right of the main screen, top- allined.

As you said when you plug the monitor before booting it gives a bad resolution, I believe adding a particular resolution in .profile would solve this issue.

Open the terminal and run the following command.

xrandr

Note the display device name from the output.In my case its eDP-1.

next run the following command

cvt 1920 1080

Copy the whole Modeline from the output.

In my case it is as follows

"1920x1080_60.00"  173.00  1920 2048 2248 2576  1080 1083 1088 1120 -hsync +vsync.

And run the following command:

sudo xrandr --newmode "1920x1080_60.00"  173.00  1920 2048 2248 2576  1080 1083 1088 1120 -hsync +vsync

NOTE the command sections after --newmode are copied from the output I got in the previous step.

Now add the newly created mode for your display device.

sudo xrandr --addmode eDP-1 "1920x1080_60.00"

Finally Apply the new resolution in the Display settings. Select the "1920x1080" resolution as your preferred resolution.

IMPORTANT: To make Ubuntu remember the new created screen resolution at next start, you have to edit your .profile. Use any text editor, for example:

vim ~/.profile

add the last 2 commands to the end

Save and reboot. Hopefully the system will detect 1920x1080 resolution in both your displays.