OldBeefer - a blonde you say. I'll hop in the car and pop over to Bath - it's on the way back from my dear old Mum. Perhaps I won't take Mrs AA that day
The router will be managed by a browser (what you use to view this site). She will have to access the router's control panel, find the security section, and follow the instructions. Netgear's support is good, and free for life, so she could get them on the phone to talk her through it.