how the player control on volume in the game?

hello! at my main menu i want to ask how do i can make in the main menu a Gauge that will give to the gamers an option to contol the volume that gonna be on the game?

You can use a horizontal or vertical slider to allow the player to chose sound level.

You change sound level globally by changing the AudioListener.volume, or indivudually for each sound or group by changing the AudioSource.volume. Note that those are two different properties, they just look alike.