A:Answer To program your Insignia™ - 43" Class F30 Series LED 4K UHD Smart Fire TV (Model NS-43F301NA25) to power on to a specific input, such as a cable box, follow these steps:
Turn on your TV and cable box.
Press the "Home" button on your TV remote to access the Fire TV menu.
Navigate to the "Settings" menu, located at the top of the screen.
Scroll to the right and select "Display & Sounds."
Scroll down and select "Power on to last input."
Toggle the setting to "ON."
After completing these steps, your TV should now power on to the last input you were using, which in this case would be your cable box. If you want to switch back to the Fire TV menu, simply turn on your TV while the cable box is off, and it will default to the Fire TV menu.