XF 1.5 How dose one change Link image?

Hay Xenforo community I was just wondering is there a way to change this image this.PNG that replaces your link when you share the website address in places like skype or facefook?
I would like to change it to another image.
any help would be appreciated thanks.
 
The problem I am having is the file becomes black and white when I try to change the logo... Any suggestions on how to do this in photoshop?
 
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