Netgear56 C3000 Cable Modem Password Change, not reset

My laptop that uses a Netgear56 C3000 cable modem was hacked yesterday and I had just begun to get pop-ups that told me my wi-fi connection was insecure because my modem password is weak.  Was told to change my modem password but my 90 days are up so Netgear won't help.  I know and have the original one taped to the bottom of the modem but don't know how to change it. Everything I see is about rebooting and going back to the original. I don't need that; I need to change it altogether.  Anyone know how and who is willing to share that information? It will be appreciated.  Thanks, Carole