Run the command as Normal user(Not as Root user)
$ xrandr--------->To Show Conneted Display (default,VGA1..etc--Hereit is default)
VGA1 connected primary 1024x768+0+0......
$
$ cvt 1360 768 60
Modeline "1360x768_60.00" 84.75 1360 1432 1568 1776 768 771 781 798 -hsync +vsync
$
$ xrandr --newmode "1360x768_60.00" 84.75 1360 1432 1568 1776 768 771 781 798 -hsync +vsync
$ xrandr --addmode default 1360x768_60.00
$ vi ~/.xprofile
xrandr --newmode "1360x768_60.00" 84.75 1360 1432 1568 1776 768 771 781 798 -hsync +vsync
xrandr --addmode VGA1 1360x768_60.00
xrandr --output VGA1 --mode 1360x768_60.00
$
$ sudo reboot
=================================
$ xrandr
Screen 0: minimum 320 x 200, current 1360 x 768, maximum 32767 x 32767
VGA1 connected primary 1360x768+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
.........
$ xrandr--------->To Show Conneted Display (default,VGA1..etc--Hereit is default)
VGA1 connected primary 1024x768+0+0......
$
$ cvt 1360 768 60
Modeline "1360x768_60.00" 84.75 1360 1432 1568 1776 768 771 781 798 -hsync +vsync
$
$ xrandr --newmode "1360x768_60.00" 84.75 1360 1432 1568 1776 768 771 781 798 -hsync +vsync
$ xrandr --addmode default 1360x768_60.00
$ vi ~/.xprofile
xrandr --newmode "1360x768_60.00" 84.75 1360 1432 1568 1776 768 771 781 798 -hsync +vsync
xrandr --addmode VGA1 1360x768_60.00
xrandr --output VGA1 --mode 1360x768_60.00
$
$ sudo reboot
=================================
$ xrandr
Screen 0: minimum 320 x 200, current 1360 x 768, maximum 32767 x 32767
VGA1 connected primary 1360x768+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
.........