Drag your new image file directly on top of the small icon in the top-left corner of the Get Info window. Release the mouse, and the icon will update instantly. Method 3: Customizing Folders in macOS Tahoe 26 (and Later)
For best results, use a square image with transparent background (e.g., PNG) and size around 512×512 px. how to change the image of a desktop icon mac
Here’s a step-by-step feature guide for . Drag your new image file directly on top
If you have your new icon image already on your desktop, this is even faster. Right-click the target folder/app →right arrow ( Command + I ). how to change the image of a desktop icon mac