Stereo output from the headset in nRF5340 Audio CIS mode

[Junichi]

Currently, I'm using nRF5340 Audio on a homemade board, and I've managed to get the sound input from the gateway as a LINE input and the sound coming out of the headset, but the sound only comes out of the headset in mono.

I want to get stereo output from the headset in nRF5340 Audio CIS mode, but what should I set and how?

[Junichi]

Additional information.
The I2S bit length is 16 bits on the gateway side and 32 bits on the headset side.