Checkbox programming visual studio C#

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I have a problem while programming a checkbox in Microsoft visual studio .windows Form application. My project is about designing a font dialog box see the photo pls help. when I check the checkbox it work but when unchecked nothing happen to the test label example: i have a label called Test Sample and 3 checkboxs one of them is bold the other is italic and last one is underline.when i click on all of the three the test lable changed but when uncheck one of them nothing happens Thank you for your time..