How to: Designate a Windows Forms Button as the Accept Button Using the Designer
On any Windows Form, you can designate a Button control to be the accept button, also known as the default button. Whenever the user presses the ENTER key, the default button is clicked regardless of which other control on the form has the focus. The exceptions to this are when the control with focus is another button — in that case, the button with the focus will be clicked — or a multiline text box, or a custom control that traps the ENTER key.
The dialog boxes and menu commands you see might differ from those described in Help depending on your active settings or edition. To change your settings, choose Import and Export Settings on the Tools menu. For more information, see Working with Settings.