How to set the icon like graphic in the Work in Progress thread?

Hi,

Please can someone tell me how to set the icon-graphic that is shown next to the thread title in the work in progress forum?
I started a thread, and it had a wireframe
But now I have updated the first post to have a render and would like the forum thread to reflect this.

Thanks in advance

Martin

[SOLVED] the title picks up the first attachment
So ‘Go Advanced’
Remove all the attachments except the one that needs to appear in the title to make this one first in the attachment list
Add back all those you need in the post
And, hey presto!