Hello @michaelokraj
That icon comes from the font awesome library/font.
You can overide and change the icon number like this:
Go into Page > Settings > Add Code and in the Header add this:
<style>
.fa-chevron-up:before {
content: "\f164";
}
</style>
And you should have a thumb up icon.
Go to Font Awesome and pick the icon/number you want to use.
Hope this helped! 
/ Johny