Beta 1760TMC 600 Instructions For Use Manual page 62

Press the up button to increase the emissivity; prolonged pressure
will continuously increase the emissivity.
Press the down button to decrease the emissivity; the prolonged
pressure will continuously decrease the emissivity. Press the OK button
to confirm the current emissivity and exit the emissivity adjustment
interface.
Press the back / on button to exit the emissivity setting interface, the
emissivity value is not changed.
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