How can I extend the wifi to my room?

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There is no device that will automatically pick up the wifi and new password when its changed. you always have to enter the new password manually. If your paying for the internet, I would have the modem located in your room with your own password for it so the kid can't get into the modem to change it. The password for the wifi you would be able to give out with no worries of anyone changing it. If you dont wanna do that then you could always talk to the kids parents and explain what is going on. hope that helps!