ShareThis in header rather than content type?
Please try the following:


Go to menu Structure>Blocks. 
find the ShareThis block.
set the block region settings for the theme you are using
go to block configuration and make sure the block is visible for all required pages, content types, roles, users
go to menu Configuration>Web Services>ShareThis
go to 'Advanced' section
find 'Location' settings
select 'Block' to select the ShareThis widget should appear as a block and not in a node content.