private void buttonAddUser_Click(object sender, EventArgs e)
 {
     signIn = new SignIn(true, false);
     signIn.Show();
     this.Hide();
 }
 private void buttonAddAdministrator_Click(object sender, EventArgs e)
 {
     signIn = new SignIn(false, false);
     signIn.Show();
     this.Hide();
 }
 private void buttonUserSingIn_Click(object sender, EventArgs e)
 {
     signIn = new SignIn(true, true);
     signIn.Show();
     this.Visible = false;
 }