Settings.Default.server = txt_server.Text;
Settings.Default.user = txt_login.Text;
Settings.Default.password = txt_password.Text;
Settings.Default.bdname = txt_bdname.Text;
Settings.Default.Save();
if (Settings.Default.CallUpgrade)
{
Settings.Default.Upgrade();
Settings.Default.CallUpgrade = false;
}
// Далее использование настроек.