If your extender is showing you solid blue light ,it means extender is already configured with the router and if you want to reconfigure it again. In that case you need to reset your extender.
> After the reset, press and hold the wps button from the extender for at least 3 seconds and then within 2 minutes press and hold the wps button from the router for at least 3 seconds
> Now it will show you blinking blue light and once it shows you solid blue light ,it means extender is configured
Note- Make sure your extender is plugged in with in 10 ft. from the router in order to setup this up through wps