On your other TV, you probably have an option to scan for either antenna(OTA digital and analog) or cable channels.
On the Roku TV, I believe it will just scan for whatever it plugged into the live tv input. (that input on the back of the tv for coaxial connectors/screw on). If you attach a HDTV antenna, then will scan for OTA digital channels. If you connect your cable company coaxial to this input, then should scan for the channels available to you through the cable package (including the OTA channels if included).
If you are connecting your cable box (rather than the cable coaxial) via HDMI, then you will most likely have to setup a HDMI input to recognize your cable box in order to see your cable channels. (Settings/TV Inputs)
To Scan for Channels when using the coaxial connection... (Settings/TV Inputs/LiveTV/Scan for Antenna Channels)
Feel free to post back if you need more help or if I am misundertanding what you are trying to accomplish or your setup.
Roku Community Streaming Expert
Just another Roku user... I am not a Roku employee.
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