private void signOutToolStripMenuItem_Click(object sender, EventArgs e)
        {
            UserInformation.Clear();

            using (IntroScreen iS1 = new IntroScreen())
            {
                this.Hide();
                iS1.ShowDialog();
                this.Close();

            }
        }
 private void backButton_Click(object sender, EventArgs e)
 {
     using (IntroScreen mTutorProgram = new IntroScreen())
     {
         this.Hide();     // hides current
         mTutorProgram.ShowDialog();
         this.Close();
     }
 }
        private void signOutToolStripMenuItem1_Click(object sender, EventArgs e)
        {
            DialogResult dialogResult = MessageBox.Show("Are you sure you would like to exit?", "Sign Out",
                MessageBoxButtons.YesNo,
                MessageBoxIcon.Exclamation);

            if (dialogResult == DialogResult.Yes)
            {
                UserInformation.Clear();

                using (IntroScreen iS1 = new IntroScreen())
                {
                    this.Hide();
                    iS1.ShowDialog();
                    this.Close();

                }
            }
        }