Changing the resolution of the monitor through a terminal is quite simple, and faster than using any graphic tool.
We open a terminal and put:
$ xrandr
That will return a list more or less similar to this:
Screen 0: minimum 320 x 200, current 1024 x 768, maximum 4096 x 4096
VGA1 connected 1024x768+0+0 (normal left inverted right x axis y axis) 310mm x 230mm
1024x768 85.0*+ 75.1 70.1 60.0
1280x1024 60.0
1152x864 75.0
832x624 74.6
800x600 85.1 72.2 75.0 60.3 56.2
640x480 85.0 72.8 75.0 66.7 60.0
720x400 87.8 70.1
Now we just have to simply write:
$ xrandr -s [Nro]
Where [] It is the number of the line where the resolution that we are going to put is found, starting from line 0 (Zero).