title: Set default value by textbox in C#
body: <ul>
  <li>I'm developing an application. I have a button btnSendEmail to send a
  password email from server to user email. My application is able to
  send a email but It need to know the password of my PC. In the
  future, if I build this application to another server, I also need to
  know that password of that PC. Therefore, I have a form with two text
  boxs: Email server and Password server. How can I set up that one
  time, and set that value to default value. </li>
  <li>For example, I wanna set
  server email is abc@gmail.com and password is 123456. It doesn't
  change until I change texts from two text boxs. Then I build to
  another PC, I can change to xyz@gmail.com and password is 234567. Is
  there any way to do that?</li>
  </ul>