// If you double click, it will select the sounds
    private void Form3UpgradesGunSounds_MouseDoubleClick(object sender, MouseEventArgs e)
    {
        if (e.X > 36 && e.X < 336 && e.Y > 35 && e.Y < 93) // FireTankCannon100
        {
            _tankCannon100 = true;
        }
        else if (e.X > 336 && e.X < 670 && e.Y > 35 && e.Y < 93) // FireTankCannon120
        {
            _tankCannon120 = true;
        }
        this.Close();
    }
    public bool GetTankCannon100()
    {
        return _tankCannon100;
    }
    public bool GetTankCannon120()
    {
        return _tankCannon120;
    }

public void MoleShooter_MouseClick(object sender, MouseEventArgs e)
    {
        // ...
        Form3UpgradesGunSounds fr3UpgradesSounds = new Form3UpgradesGunSounds();
        bool _f1tankCannon100 = fr3UpgradesSounds.GetTankCannon100();
        bool _f1tankCannon120 = fr3UpgradesSounds.GetTankCannon120();

        if (_f1tankCannon100 == false)
        {
            F1TankCannon100();
        }
        else if (_f1tankCannon120 == true)
        {
            F1TankCannon120();
        }
        // ...
    }

    public void F1TankCannon100() { /*. Do something .*/ }

    public void F1TankCannon120() { /*. Do something .*/ }

public partial class Form2: Form
    {
        public static bool BolleanProperty { get; set; }
        // ...
    }

public partial class Form2 : Form
{
    public static bool BolleanProperty { get; set; }
    static Form2()
    {
        BolleanProperty = true;

    }
    public Form2()
    {
        InitializeComponent();
    }
}

private void Form1_Load(object sender, EventArgs e)
        {
            label1.Text = Form2.BolleanProperty.ToString();
        }