How to change the recent files smart folder icon in the dock?
You can easily change any icon folder from any picture you want (copy the picture you want -&gt; get info of the folder -&gt; click the actual picture folder -&gt; paste the new picture).
From Apple support to change picture of folder :
Create custom icons for files or folders on Mac
You can create a custom icon for any file or folder using your own pictures, icons downloaded from the web, or the icon from another file or folder.
Use your own picture or a picture from the web

On your Mac, copy the picture you want to use to the Clipboard.
One way to do this is to open the picture in the Preview app , choose Edit &gt; Select All, then choose Edit &gt; Copy.

Select the file or folder whose icon you want to replace, then choose File &gt; Get Info.

At the top of the Info window, click the picture of the icon, then choose Edit &gt; Paste.