if you have the i68+ than yes you can change.go to settings>phone setup>than display characeristic. you can change it there.
if you have a i68(not plus +)than no you can not change them sorry
_________________
HARDWARE VER:HGY718_M6225_V1.0
SOFTEARE VER:YG718-03-SIV100B-NOLOGO-
EN12-BTNO-900-V004
FLASH TYPE:S71PL127NC0:
BUILD TIME:2007/11/29 18:25
BUILD AUTHOR: WANGZHIJUN
also own sciphone i68 with javquisoft firmware 3.0
and my iphone 3G