Show unread posts since last visit

Hi, a member of my forum has asked for the feature "Show unread posts since last visit", but I can't seem to find how to activate it. Please could you help? Many thanks!

Its enabled by default
Attached a screenshot of where it is at

Sorry, I'm still all at sea with this one. Please could you give me numbered steps to follow, starting with


1. Log in as admin


Many thanks!

If your theme looks like this website.
The user just needs to login does not require admin.
Then click the dropdown arrow next to the username in the top right cornor and that popup like the screenshot shows will appear.

Brilliant, thanks!