First log in to the WiFi network with the default password.
Then log in to 192.168.1.1 / 192.168.0.1 (this IP address differs from router module to router module. Please check your router for the correct IP)
Then use the username and the password mentioned on the Router Sticker...
For to WiFi settings and now you can change the display WiFi name and the password. Ones confirmed Router will re-start.
Now search for WiFi and it will show the new display name and use the new password to log in.