Hi George. Keith here (Not.Silent). Before booting up Steam, to guarantee your chosen screenshot appears for your scenario when publishing, go into the Screenshots folder first and put all your screenshots in new named folders, leaving nothing 'except' your chosen screenshot file. That is one way. Another is to rename your screenshot to just a 1. Also from my experience there seems to be a limit of about 20 that you can use per publishing. This limit is when scrolling through. Once chosen for the main one to appear, you cannot change this. However, upon realising you have made a mistake, you can Delete the published scenario and start again (assuming you still have it in Build) and follow as I have mentioned above. Let me know if you do not know how to Delete etc.