Changing Resolutions of Screen and Login Window

Every time I install Ubuntu, the biggest problem will be changing the Resolution of the desktop and login window.

If I want "Visual Effects", I will have to enable "Nvidia accelerated graphics drivers"; However, whenever I enable it, the Screen Resolution will change to "50", although it looks the same as "85". Changing the number of rate at "desktop/gnome/screen/default/0" in "Configuration Editor"( gconf-editor ) won't work. I doubt that this is a BUG.

After I turn on "Visual Effects", the "close", "maximize", "minimize" buttons etc. of windows besides Firefox will disappear unless I install "compizconfig-settings-manager".

Next we will change the resolution of login window.
sudo dpkg-reconfigure xserver-xorg
Delete the resolution you don't need.

An alternative way will be configuring "/etc/X11/xorg.conf", see Here.