Did you go to https://community.clickteam.com/passport to download the latest mac installer as Yves recommended?
If that doesn't work you have to right-click on the CF2.5 app and select Show Package Contents. You will see the Wineskin.app inside which you click on and it comes up with a menu with 'Set Screen Options'
You can experiment with the different settings. The issue is discussed in full in this forum thread: