[deleted] You could do this via CSS. You'd need to target the :before
element of each icon. So, for example
Then, study the CSS applied to this tag
Now if you go to the Font Awesome website (example here) you can then choose an icon you'd like to replace it with. Note, that if you are using the "free" version of FA, you're restricted in terms of choice, so you can't use any identified as "pro"
Once inside the settings for the icon you've chosen
You need the 4 character value - in this case, f086
. Copy this reference.
Now go back to your CSs
Replace the value in there with the new one you've just copied. Remember that you must include the backslash before the actual reference, otherwise, it won't work.
Press enter, and then you'll see your new icon.