New Galaxy S i9000 - mobile network type selection

Apr 2, 2013
In settings --> mobile networs --> network type selection, i want it to be "only 2g - power saving" in my Galaxy S i9000 ,but always turns to "3g prefered" after each reboot ,so every time i have to change "only 2g power saving" . This happens in every MIUI rom v5 i have tried.
Can you fix it please to keep the setting i have done ?