Enter the PEOPLE tile.
On the left will be:
Touch "What's New"
Drag from the top down to expose the hidden bottom menu.
A pull-down style menu appears. Select either Facebook, Twitter or All depending on which feeds you want to view. Personally, I think that the options should be more touch-oriented and less mouse-and-pointer menu oriented at this step, but that is a design quibble and I'm sure old habits die hard.
The problem, Jason, is that you're approaching things from an iOS/Android paradigm where you expect a button to be superimposed over the screen that turns a filter on or off, or to click an onscreen or hardware Menu button that brings up a pull down menu.
Which is perfectly reasonable for someone who has been playing with Android and iOS products for the last several years to expect.
I just found out how to dig deeply into the News tile and pin favorite sources to the Start screen as live tiles - a very cool feature. Digging into the Modern-UI apps can be a frustrating process, some genuinely do not have features or integration that they *should* have, others have those features but they're buried. It is still a very rough, evolving platform and many of the apps could use significant polish, but there are some very cool features hidden in there, too.
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