Maybe this might make a difference. With the Viber app installed on your phone, go your Settings >> Applications manager, find Viber, and select it. Tap the 'Force stop button', uncheck the 'Show notifications' box, tap the 'Clear data' button, then tap the the 'Uninstall' button. If part of your previous setup data was still left over from before this should clear it up. Now using Google Play to install Viber again, you'll need to log into your Viber account again since it was cleared out.