Hi Eva,
I didn’t get exactly what you mean. You can add featured images instead of using icons in featured image. If you want other than this then you need code customization for it or hire a developer to fix it but We recommended not to change the code because if you change the code then while updating to our new version all your customisation code will be lost. So better make child theme and first unhook the functions and the edit the code.
http://codex.wordpress.org/Child_Themes
Thank you!
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