interesting i guess i never noticed the default share buttons don't technically share much of anything..
Alternately you can use the numerical post sharing permalinks found next to the like and reply buttons of every post. At one time i used a font awesome icon next to to corresponding numeral to draw attention to the hidden links.. I use shareaholic buttons on the index page. Im not sure specifically what or where you needed the buttons but for threads i like the numerical permalinks the best. For the sidebar you cant beat the options sharethis or shareaholic give you.. https://xenforo.com/community/resources/make-post-sharing-more-obvious.3405/