On your WP dashboard, go to Settings ->AddThis Share.
Under the ‘Basic’ tab select the style of share buttons you want.
It’s a good idea whilst on this page to register for visitor analytics.
Then click the ‘Advanced’ tab. On that page you can select where the share buttons go.
You can also set more options as well.
I can only suggest two possible reasons then.
You need to be registered with the developer of AddThis. You should have an
AddThis profile id in the top right hand corner of the AddThis page.
Register at the bottom of the page if you haven’t already done so.
But if you have already done that. Write down that id, deactivate the plugin and delete it.