You need to store configuration settings for a form so that they are remembered the next time that the form is shown.
Use the Application Settings functionality, which is configurable at design time in Visual Studio.
How It Works
The Application Settings functionality, first introduced in .NET Framework 2.0, provides an easy-to-use mechanism through which you can save application and user settings used to customize the appearance and operation of a Windows Forms application. You configure Application Settings through the Properties panel of each Windows control (including the main Windows Form) in your application. By expanding the ApplicationSettings property and clicking the ellipsis ...