App icons for iOS or Android should be put into the Media Folder. This will be the icon that appears on the device that you tap to start your app. App icons should be 512x512 pixels.
The icon needs to be 512x512 pixels. To set the icon for you app first click on "Edit App".
Go to the "General" tab.

Go down to where it says "Icon". Here is where you will click to access the icon you uploaded to the Media Folder. The icon should be 512x512. You can also set an alternate icon for your Android app if you are building for iOS and Android
