Changing screen resolution of X Server on Linux hasn't been easy. It usually requires manual of configuration file
/etc/X11/xorg.conf.
The most easy way I could find is using command
dpkg-reconfigure -phigh xserver-xorg, which requires superuser right. You can do a
su root first or simply
sudo dpkg-reconfigure -phigh xserver-xorg.
The result of this command is actually a modified xorg.conf.
Correction: dpkg command is only available on Linux distribution that uses DPKG package manager, like Ubuntu and Debian. While other popular distributions like Redhat Linux and SUSE Linux use RPM.