how i can change resolution screen in LOGIN KDM opensuse 11.3 kde 4.6?


first installation opensuse 11.3 and kde 4.4 after update to kde 4.6, work fine, but problem is login screen is low like 640x350…? i wanted to change from low resolution to high 1024x768?
when i start opensuse and begin to login was low resolution and log in my user and it’s low resolutiona dn i change screen from setting system (kde) after change high display is works fine and rebbot same low resolution for LOGIN MANAGER how i can change it???

nothing respond…i need this help…thankyou