Sorry, Andrew, I'm not following any of this...
As I said, I'm completely new to all this.
If I add the codes pasted above:
.social-block a,
.social-icon { color: #39c6f4; }
.social-block a:hover,
.social-icon { color: #414a9e; }
Only the ones in the Menu bar change, the ones in the footer don't.
If I'm following to understand your response, both should in principle change with those codes?