Are you sure you've using latest CB Connect? Your button doesn't look anything like the one included with CB Connect. See the screenshot found on the below page for what the buttons should look like.
www.joomlapolis.com/cb-solutions/cb-connect
If they don't look like that then you may have a CSS conflict coming from your Joomla template. The only way to restyle them is with CSS. The icons can not be changed without altering source or using CSS to display a different fontawesome icon.