Customizing an app icon in macOS is simple: Navigate to your Applications folder Right-click the app you wish to customize Select “Get info” Drag and drop your custom icon on top of the default one.

you could also change the look of the app icons? Indeed, if you're tired of the look of that dusty ol Mail app or if you just want to add a personal touch to your phone, you can change the look of ...

It shows one or two app icons and the rest are stored in the system tray. At times, you might want to display all the icons so that you can quickly click on any of them and open them on your computer.