how can i change to 3G.? its always at 4G.

how can i change my h811 G4 to work on 3G only.. as it shows 4G. i dont need that speed just for whats app and facebook..
i have changed in settings/more/mobile networks/networkmode/wcdma only.. but its still on 4G.? when i had my LG G2 it was on 3G....
according to a webpage this is my band

Movistar
3G 4G
B2 / 1900 MHz. B2 / 1900 MHz.

B5 / 850 MHz.


GSM 1900
CDMA 800/1900
UMTS/3G
HSDPA/3.5G
HSUPA o HSPA+/3.75G
LTE/4G

thanks