Default [Q] Priority 2g 3g - contacts at account google

In Brazil, the 3g is a s*it, unfortunately

how i can change the priority for 2g when i'm not using the data, only calls and when i activate the data the signal change to 3g?

is it possible?



when i add a new contact the default is save in SIM card. Is it possible change the default to google account?

tks