Sometime Today, Sameer Shinde assembled some asciibets to say:
How can I change the screen resolution in RHL7.1 I checked the control panel but I didn't found any tool to change the screen
vi /etc/X11/XF86Config or XF86Config.4 (not sure which one you use).
Scroll down to the Screen section for the driver that you use. You will find Display subsections there. Just change the order of the modes in there. If you want to set a default colour depth, then before the first Subsection line, add DefaultColorDepth 16
Philip