Random button location is only on 1 line

I'm trying to make a sort of aimtrainer and I want a button to randomly change location when you click on it. I managed to randomize the coordinates but the button always stays on 1 line (top left to bottom right). How can I have the button also 'spawn' on other places? Thx

'''

public partial class game : Form
    {
        Random x = new Random();
        Random y = new Random();

        public game()
        {
            InitializeComponent();
        }

        private void game_Load(object sender, EventArgs e)
        {

        }

        private void button1_Click(object sender, EventArgs e)
        {
            int cox = x.Next(100, 1800);
            int coy = y.Next(100, 900);

            button1.Location = new Point(cox, coy);
        }
    }

'''