Add code to your extra.less template:
Code:
/* Icons for Login and Register buttons */
.p-navgroup-link.p-navgroup-link--textual.p-navgroup-link--logIn:before {
font-family: FontAwesome;
content: "\f090";
color: #E6BB5C;
padding-right: 5px;
}
.p-navgroup-link.p-navgroup-link--textual.p-navgroup-link--register:before {
font-family: FontAwesome;
content: "\f084";
color: #E6BB5C;
padding-right: 5px;
}
/**********/
More information
https://xenforo.com/community/resources/...tons.6000/