This TV doesn't need a Fire Stick because the Fire TV experience is already built-in. If you want to use your cable box, you need to connect it to the TV using an HDMI cable and you need to use the cable remote to change channels. Try the Power On feature, when enabled, the TV turns on displaying the last used input. To activate it, go Home > Settings > Display & Sounds > Power On and select Last Input. 4K - UHD streaming needs at least 25 Mbps.