private void addCasButton_Click(object sender, EventArgs e)
{
addManButton.Hide();
addCasButton.Hide();
checkStockButton.Hide();
checkCustButton.Hide();
checkPreButton.Hide();
AddManLabel.Hide();
AddCasLabel.Show();
fnameBox.Show();
fnameLabel.Show();
lnameBox.Show();
lnameLabel.Show();
staffIDBox.Show();
staffIDLabel.Show();
addressBox.Show();
addressLabel.Show();
phoneBox.Show();
phoneLabel.Show();
emailBox.Show();
emailLabel.Show();
unameBox.Show();
unameLabel.Show();
pswdBox.Show();
pswdLabel.Show();
CasAddbutton.Show();
ManAddButton.Hide();
backButton.Show();
clearButton.Show();
}