Do you mean this one?- http://yourdomain.com/index.php/dashboard/welcome/...

Use the 'Intelligent Search'.. search for 'Welcome'

There's no way to make it the first thing people see when they log-in anymore?

It is the first thing you see when you log in; I think you'll only see it once when you first log in. It's a lovely welcome to run people through Concrete5... seeing it every time they log in may end up being an annoyance for most people.

Afterwards, every time people log in, they will be met with the 'Welcome Back'/ News page which has all the latest updates from Concrete5 and beyond.

The list includes -
Tutorials and Tips,
Featured Themes and Add-ons,
Blog updates,
Tech News,
Marketplace Spotlight,
Karma winners,
Member Spotlight,
Showcase Spotlight
and much more..

I think this keeps everything fresh and interesting. However, Concrete5 does allow you make any change you want so if you'd like your clients to see that Welcome page every time they log in, you can just go ahead and adjust it to your requirements. :)

That's actually what I meant.. The welcome back screen. It used to show that but ever since I updated it's showing a dashboard page instead..
How do I change it back to the welcome back screen?

I think it only appears after you've been logged out for quite a while. I'm not sure of the time but I'm guessing around 24 hrs maybe?
I'm on 5.5 and I was also wondering why it doesn't appear every time I log in so I have come to the conclusion that it won't show up constantly if say I'm logging out and in after an hour or so.

However, If you still need to reach that page you can do so by hovering over the dashboard and selecting 'News' (Third one up from the bottom).

Sorry I couldn't be of more help. Maybe someone else can shed some light on this!?