#create a file /etc/X11/xorg.conf.d/40-monitor.conf
vi /etc/X11/xorg.conf.d/40-monitor.conf
#Add these lines
Section "Monitor"
Identifier "VGA1"
Modeline "1368x768_86.00" 127.50 1368 1456 1600 1832 768 771 781 810 -hsync +vsync
VendorName "Panasonic"
ModelName "TH-42PV60"
Option "PreferredMode" "1368x768_86.00"
EndSection
#save
If you have two screen, the above settings might not default the screen to the required solution. So maybe you want to add these lines to the file ~/.xprofile :
xrandr --newmode "1368x768_86.00" 127.50 1368 1456 1600 1832 768 771 781 810 -hsync +vsync
xrandr --addmode VGA1 "1368x768_86.00"
xrandr --output VGA1 --mode "1368x768_86.00"
Or just this line if you want to use the combination above:
xrandr --output VGA1 --mode "1368x768_86.00"