If you don’t like how your files and folders look in Gnome, you can use a different icon theme. If it’s only a specific icon you’d like to swap, it is very easy to change icons in Gnome 3. You can change any file or folder’s icon for a custom one as long as you have your own icons in SVG or PNG format.
Note: while this tutorial is for Gnome 3, the same trick can be done on other Linux file managers and desktop managers.
Start by firing up your favorite file manager to find the file or folder whose icon you aren’t quite fond of.
Right-click on the folder and select “Properties.” Although it’s not apparent, the image on the top left is not just a preview of the active icon. It’s also the point where you can change the icon, as it works as a button. Click on the image, and a file requester will pop up.
Point the file dialog to the image file you want to use as an icon. It’s worth noting that officially, Gnome also supports the XPM format apart from SVG and PNG files. Still, it’s suggested you avoid it since it’s only “supported due to backwards compatibility reasons.”
When you return to the main Properties window, the icon preview on the top left of the properties panel will have updated, showing the image you selected in the previous step.
Close the Properties dialog, and your file or folder will, from now on, show up with your custom image as its icon.