Originally Posted by mrodgers
Yes, understood. That wouldn't be my problem.
If I am at work and my wife is at home, we are both on wifi. If I call/text my wife with Viber and she has left home to run to the store, I want to make sure that she would not pick it up on 3G while she is out and use up limited data. That is why I want to know if there is a setting to only use wifi.
Unfortunately, Viber does not have this option - it is programmed to stay available at all times. However, remember that you can simply choose to manually not take calls when you are connected to 3G. Think of Viber as a "substitute" to your cellular service - sometimes you're available (physically) to receive the call, but choose not to take it, and only get back to that person later.
About moving to the SD Card - please go through Viber's settings inside the "More" menu. You should find this option there.