Need help with forum display

[midlife crisis]

Ok so I'm old and slow, either that or I am good at overlooking what is right under my nose. After logging in, the forums display differently on my different computers. On the system I am sitting at now the posts display newest on top down to the original on the bottom. It drives me nuts and I can't seem to find where to reverse it so the original post is at the top and successive posts are below. Can someone please point out the location/setting to resolve this?

Thanks