My screen's resolution is 1024x768 and when I installed Ubuntu it was forcefully in 1440x900. I changed it in my account and again I've to change it in another standard account. I don't know any way to change it in login screen. Also when shutting down that black screen with some commands also appears in 1440x900. I don't know why Ubuntu force itself to be in 1440x900. I want 1024x768 in whole way.

I don't know whether it is required but I have Intel chipset 128 MB.