Thanks Anoscope and Doc ... here's how I've resolved it.
In the topic, I now ONLY use the link to "Last Post By" which takes me to the end of the posts in the topic, and I scroll backwards if I need to.
Doc's suggestion does indeed sort the topics, but not the the posts within the topic. I feel that it would be a useful feature (but perhaps not possible?) to have a permanent setting where all topics display the most recent post first, through to the oldest. You'll see what I mean when you reply to a topic, it shows the most recent post first! This is exactly what I mean.
Thanks for the suggestions.