How to use custom app icons on a Mac
Changing an icon on a Mac is pretty straightforward. It does not require a third party application as long as you change the image to another .icns file. It’s not difficult if you just copy another app’s icon to your laptop or desktop.
But if you want to customize your own images, you will need help. Apple requires these icons to be an .icns file, and as you might have guessed, most images are not saved in .icns format; you will have to convert them. We can do this with a free tool called Cloud Convert.
All you need to make it work is a square image and a tool like Cloud Convert to do the conversion. Once converted, you can follow the first part of this tutorial to replace any icon with a new custom icon.
Change the app icon
1) Open Finder to access the application.
2) Open applications to see a list of all the applications on your computer.
3) Right click on the app to open the context menu.
4) In the menu that opens, click on Get information.
5) Drag the icon and drop it on the icon in the application information window.
Convert images to .icns format
1) Go to https://cloudconvert.com/
2) Click Select File to start the process.
3) In the list that opens, select location of the file.
4) Select image that you need to convert.
5) Click on Open to upload the file to CloudConvert.
6) Open the Convert to drop-down menu to select the format.
7) Select ICNS in the menu that opens.
8) Click Convert to download the icon in .icns format.