Extender

I have a netgear extender and a different brand router. However, the router was not working as well as I thought it should and purchased a new (Netgear) router. Unfortunately, the new router did not work as well either and chose to go back with the previous one. Now, my extender does not recognize my old router. Instead, it is still using the same name given for the newer router. How can I switch it back to the old router?

Thanks,

-W