What are the factors that affect the choice of display resolution and colors of a computer?

Basically it boils down to video card and monitor. Your video card is only capable of certain resolutions and color schemes, and your monito is only capable of displaying certain resolutions and color modes. Your computer and monitor communicate with each other and decide what the various resolutions and color schemes that you will have access to. If you do not see the resolution that you wish to use, the cheap way to attempt to resolve this is to update your video drivers. Otherwise you will need a new monitor.