In Yosemite, the location of the default browser setting has been moved to the System Preferences menu. This will load a list of general system options. Select the browser that you want to use from the list of available browsers. You'll need to install your new browser before you can select it from the list.
اضغط على قائمة آبل واختر "تفضيلات النظام". اضغط على خيار "عام". اضغط على قائمة "متصفح الويب الافتراضي".