I think you're referring to 'Infinite Scroll', which can be enabled/disabled in your settings.

On the top right of the web page, choose your username to drop the menu, then 'My FlyerTalk'
On the left side, choose 'Edit Options' and then scroll down to 'Thread Display Options', and in that group, there is an option for 'Infinite Scroll'

If you disable this option - and then scroll to the bottom to Save changes, it should do what you want