Use a type selector in the to override the default styles of your ToolTips
<?xml version="1.0"?> <mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"> <mx:Style> @namespace mx "http://www.adobe.com/2006/mxml"; mx|ToolTip { fontFamily: "Arial"; fontSize: 19; fontStyle: "italic"; color: #FF6699; backgroundColor: #33CC99; } </mx:Style> <mx:Button id="b1" label="Click Me" toolTip="This Button does nothing."/> </mx:Application>