Hi there,
I did some digging on this, and checked out your icons (the square Twitter icon and the square RSS feed), and yours actually look more up-to-date to me than the ones shown on the demo. The Twitter one displays the new logo!
But if it's not what you're looking for, I do understand. That said, it looks like those are dictated by the theme itself, and may not be editable.
As a premium theme owner, you can access the Premium Themes forum:
http://premium-themes.forums.wordpress.com/forum/linen
You can either browse the topics posted to see if someone else had the same question, or you can post your question; you'll get a reply from the theme creator, who will be better able to guide you on anything theme-specific!
I hope that helps you!