Hi Ronald
That option means that when swapping between the topics on the left it won't always reset back to show the 1st tab in that topic. I think it looks for a matching tab name so, for example, if topic 1 & 2 both contain tabs called 'Introduction', 'Plan' and 'Examples' and you select the 'Examples' tab on topic 1, when you change to topic 2 it will see if an 'Examples' tab exists for this topic and if found it will show this tab in topic 2 rather than resetting to the 'Introduction' tab.
Thanks
Fay