Basic Maths Header Text

Hi: I’ve installed the Basic Maths theme by Subtraction.com and I unchecked the “Show header text with your image” checkbox under Appearance>>Header to display a logo instead. When I click “Save Changes”, the checkbox is automatically checked again and the header text is back, covering my logo. Is there any other way to hide this header text or to make this checkbox work properly in this theme? the website is http://qualityparaplanning.com.au. Thanks.