
You could click on the Apple menu on the top left corner, and select Force Quit, at which point you will be presented with a list of running apps, and select the troubled application.
But a much faster way to Force Quit an app is to right click on the icon of the app in the dock (or two finger click on trackpad). You will see a menu pop up above the icon. If you hold down the Option key, you will see the Force Quit option appear. Click on it, and you’re done.


