Change of "Preferred network type" after upgrading firmware

For the product models with dual SIM slots, the option "Preferred network type" in “Settings” -> “More…” ->”Mobile networks” is only for the SIM card which is appointed to use for data service network after upgrading to:
A400CG: V6.6.3
A500CG/A501CG: V2.21.40.44_20150117_82
A600CG /A601CG: V2.21.40.39_20150117_58

(After)


(Before: both SIM cards available for setting)