Mute via Bool not working

I am trying to create a audio source that fades in and out when a box collider is triggered.
Currently, I am using mute rather than fade to check that my bool works, and it is not.

Currently, the bool works fine and is successfully changed when triggered, however the change bool value does not affect the mute/un-mute of the ‘music’ audio source.

I have tried so many variations, please help! Code below.

public AudioSource music;
public float TimeMultiplier = 5f; //Going to be used for fade
public bool No_music = true;

void OnTriggerEnter(Collider collider)
{
    if (collider.tag == "Player")
    {
        No_music = true;
    }
}

void OnTriggerExit(Collider collider)
{
    if (collider.tag == "Player")
    {
        No_music = false;
    }
}

void update()
{
    if (No_music)

    {
        No_music = true;

        music.mute = true;

    }

    else

    {
        No_music = false;

        music.mute = false;
    }
        
}

Your “update” method is named incorrectly. To have the unity engine pickup implemented methods you need to ensure the case is correct of the method name. Yes they are case-sensitive. Rename your “update” method to “Update” with a upper case “U”, now unity engine will execute the code block for Update each frame.