RE: How do I change my wifi password

Those devices come pre-configured with the SSID and WPA2 key set to those listed on the label on the bottom.  Ideally for simplicity sake it's suggested they not be changed however if you still wish to do so here is the manual with all the information:

http://media.cox.com/support/print_media/internet/equipment/Netgear_CG3000D_User_Guide.pdf