i keep hearing my own voice

Far as I can tell, it's not possible to adjust mic monitoring when used with an Xbox, unfortunately.

However, apparently, if you have access to a PC or laptop, then you can download the TB App, update the firmware (if needed) and use the settings there to then adjust the mic monitoring:

https://uk.turtlebeach.com/pages/audio-hub

I found the information here:

https://www.reddit.com/r/TurtleBeach/comments/izbpsi/new_stealth_600_gen_2s_mic_monitoring/

After you record your message and choose the option to play it, is there just a flat line there? Or is here a little graphic indicating something has been recorded?

If the line is flat, then that means its not recording anything.

If there is a graphic there indicating that something has been recorded, then check your headphone settings

With your headset plugged into the bottom of your controller

- Hit the Xbox Button on your controller and instead of choosing settings, choose Audio

- Make sure the Headset Mic is set to On and headset volume and mic monitoring is turned up

- Check the headset itself just to make sure there's no mute enabled on the headset

What is with people on youtube and excess spewing just to hear their own voice....Keep the verbiage short and sweet...just like writing an internet article...

Ah, okay then
Yes, seems like that's the reason. And I have one more problem because it keeps happening. When I play the recorded video, I can hear my voice, the game audio, but I don't hear any of my friends' voice chat. Sometimes I can hear their voice, but many times I can't. How to fix this? And what audio will be recorded if I check the "Record game audio only"? I've tried to turn it on and off but seems like it keeps changing.

The correct thing is not to hear yourself, to hear your voice is because there is a return and something is wrong and bothers you and the other players, that way I believe everything is right, is there any reason to want to hear your own voice?

I think you misread my answer, I'm saying my Mic works. I know this as I created a voice note to test if my mic was not being picked up by the Xbox. I did not say that I was able to hear myself.