Our WordPress themes use font awesome icons you can change every icon present in our theme. Click on the edit icon of which section icons you want to edit. Once you click you can change the icon by changing the icon name. For example – fa fa-user, fa fa-cube, fa fa-facebook, etc…
Font Awesome provides more than 1000 icons of different categories you can check here – https://fontawesome.com/v4.7.0/icons/