How do i change my sound to mono?

Support
1

I usually use my left ear to listen to the music and my right ear to listen to my keytaps so it would be good if i change my sound mode to mono

3

That’s going to be easiest to do just in Windows itself, not Etterna.

https://support.microsoft.com/en-us/windows/make-windows-easier-to-hear-9c18cfdc-63be-2d47-0f4f-5b00facfd2e1

^ Is a Microsoft article on accessibility settings related to sound which will tell you how to do that.