Need help with my WI-FI settings on my iPhone 4S.?

I just got a new iPhone 4S today and I set the WIFI settings to connect to my houses WIFI. But whenever I turn the phone off and turn it back on the network settings go back to 4g. How can I fix this?

 Sol :- Once goto network settings, there choose the packet data settings. As from the manufactuer Data settings are the default one which iphone 4s gives priority and choose the internet connection source as wifi and set it default.

Then try turning off the phone and back it on, it should be wifi enabled by default and now you can browse.