About the Linked IN button :
I am using the JSN Boot Pro template. In Template configuration, in the SEO & System tab, there is a "Optimize Script Tags" parameters that is described as "if enabled, all script tags will be moved from head section to the end of body section"
I disabled it and now I can see the linked IN button.
I thought this may improve the website, isn't it ?
About the Pinterrest button :
In social / content plugin - like, I activated the Pinterrest button. As the other buttons it should be in the top section in article view.