Mweb wi/fi modem - how to change pin / password

[SCW]

I have an Mweb FON modem TG589vn. It appears that the login details are no longer private, everyday I see more and more unknown devices connecting to the network and it is now slowing down my connection speed.
How do I change the login details - the modem was supplied with a wireless key and a wireless pin, however one seems to only need the key to join the network?
Thanks

[HR Solutions]

I think it is the 168. Number ...... Slips my mind now, but then login with admin being username and password then u can change all the settings

[SCW]

Thanks.
I can get into the modem control panel as admin, but from there it seems the only thing I can change is the password to get back into the admin control panel??
I'm sure I am missing the obvious somewhere....