Use alacarte to change the image of an icon. This is useful when I prefer a different look of a different software item or file.
Use "Quick search" to locate the alacarte package in Synaptic Package Manager.
Click on the box next to alacarte and select "Mark for Installation". Click on "Apply".
Next, I right-click the "Menu Panel" at the top edge of the screen and click on "Edit Menus". I should see the box below:
New Item" to see the "Create Launcher" box below. I click on the icon of this box to choose my favourite image for my icon. For example, the image can be a png image.
I can choose my image in any directories.
Fill in a blank by typing the name of the application in the "Create Launcher" box. Click on "Browse..." to select the application. Then, click on "OK".
I can also right-click on the space on Desktop to select "Create Launcher..." and make a customized Desktop icon.