Cannot add new font-awesome icon onto footer/header or front-end

Question: I have changed one of the social icons in the footer to Snapchat. It seems to be there but the grey colouring has disappeared. We need it to display in the same colour as the other icons?

Answer:  Our theme old theme Claue 1, Supro, Molla, Organie, Gemmart, Unero use fontawesome 4.5, however you are using fontawesome 4.7 (fa fa-snapchat). That is the reason why icon disappear. You can see icons of fontawesome 4.5 here and choose one instead of fa-snapchat http://swwwitch.com/dl/Font-Awesome-Cheetsheet-4.5.0.pdf

Or if you want to use fontawesome 4.7, you can follow this article: https://magento.stackexchange.com/questions/224248/how-to-add-font-awesome-in-magento-2