NETGEAR AC1900 - How to change Default rout password, I have done this in past.. Can't figure it out

I have a netgear AC1900 I need to change the basic standard default password that is used to get into the Router.  I'm not talking about the network password.   It comes standard with Admin and "Password"...  I have always changed it, as in any real business environment it is a must to have this changed and secured.   I did see another posting- but it had NO information.. just a guy getting condending about nobody needs to do this but the CIA .. FBI..  was crazy- apparently doesn't work in a real business enviroment- and just wants to ream people.   I see someone else was asking but really just gave up after they got blasted by that guy.. and the thread was closed with no real answer - just that it can't be done.. of course it can...    Please if anyone has the procedure to do this simple change on the AC1900 please let me know.  Thank you in advance!