How do I navigate to 2nd windows form to 3rd windows form using back button where CS file is same only

using System;
using System.Drawing;
using System.Windows.Forms;

namespace WindowsFormsApp1
{
    /// <summary>
    /// Test form with Back and Next buttons.
    /// </summary>
    public partial class Form2 : Form
    {
        static Form2 cwForm1;
        static Form2 cwForm2;
        static Form2 cwForm3;
        static int formNumber = 1;

        public Form2()
        {
            InitializeComponent();
        }

        private void Form2_Load(object sender, EventArgs e)
        {
            if (cwForm2 == null)
            {
                cwForm1 = this;
                cwForm1.labelNr.Text = "1";
                cwForm1.Text = "Test form 1";
                cwForm1.BackColor = Color.LightSkyBlue;
                cwForm2 = new Form2();
                cwForm2.Text = "Test form 2";
                cwForm2.labelNr.Text = "2";
                cwForm2.BackColor = Color.Beige;
                cwForm3 = new Form2();
                cwForm3.Text = "Test form 3";
                cwForm3.labelNr.Text = "3";
                cwForm3.BackColor = Color.LightGreen;
            }
        }

        private void ButtonBack_Click(object sender, EventArgs e)
        {
            if (formNumber > 1)
            {
                formNumber--;
                ChangeForm();
            }
        }

        private void ButtonNext_Click(object sender, EventArgs e)
        {
            if (formNumber < 3)
            {
                formNumber++;
                ChangeForm();
            }
        }

        private void ChangeForm()
        {
            this.Hide();

            if (formNumber == 1)
            {
                cwForm1.Show();
            }
            else if (formNumber == 2)
            {
                cwForm2.Show();
            }
            else
            {
                cwForm3.Show();
            }
        }
    }
}