I found the following for Windows 8.1,
order of app buttons on the taskbar:
All open files from the same app are always grouped together, even if you didn’t open them one after the other. This is so you can see all of the previews for that app at the same time.
How do I make the last or the latest icon to always open on the right hand side. And that the first app or icon is on the left hand side. Second app or its icon always opens or goes on the right hand side (now second left). And the third app or its icon always
opens or goes to the right hand side (now third left). etc.
How do I make any and all apps or their icons to always been displayed in chronological order? First on the left hand side of the notification area and last on the right hand side of the notification area,
no matter they are all icons of the same apps or all different ones.