To update the contact information found on the footer area of all website pages, you'll just need to edit a specific footer widget.
Visit Dashboard> Appearance > Widgets.
Look for Footer#3 widget area on the right hand side, and open the contact widget inside.
You can also reach this area directly by going to: http://www.yourdomainname.com/wp-admin/widgets.php
Just replace "yourdomainname" with your website domain or URL.