XF 1.5 Twitter shows my avatar instead of picture from thread, please help

Dear Xenfolks,

Could you please help me?
When I want to tweet a thread, I click on the twitter app which is located above every thread border in my forum, and it tweets it. When I go to check on twitter in the post it shows the link and my avatar which I don't want to be shown. I want it to show the picture from my thread instead. (There is always a picture with the thread)

(That's my avatar)
Could you please tell me where I can edit it in Admin panel so it shows the first or any picture from the thread instead of my avatar?
Please use dummie language, I'm not an I.T. person.
But can fix/edit simple things.

Edit to add: It shows the picture from the threads on Google+, and Facebook. I'm only having trouble with twitter.
Last edited: