1. Right-click the title bar of your dialog-box then select Properties from the pop-up menu. The Dialog properties dialog-box will then become visible. Click the general tab then locate the caption textbox.
2. Key in your desired caption in the caption textbox then click the close[x] button of the Dialog properties dialog-box. The inputted caption should now appear on the title bar of your dialog box. Additionally, you can modify the font face and size of your MFC dialog box by right-clicking the caption of your dialog and selecting properties>general tab and clicking the Font button then choosing your desired font face and font size. Unfortunately , it will also resize the dialog box, just click and drag the selection handle of your dialog to restore it to its default size.