How to record the audio coming from my UA-25 EX?

Hello!
I've started a series of Cubase tutorials videos, so I need to record the screen, the microphone, and the audio coming from Cubase.
I use the Cakewalk UA-25 EX...so far I was able to record my voice via Input 1, but no other audio.
Just a moment ago I accidentally pressed the DIGITAL IN button (which I never used before), and I was able to record what Cubase was playing in that moment!
So the question is this: how can I record both voice&sounds at the same time? It'd be very annoying to switch the digital in every time I need to play something back.

Thanks,
Alessandro

I don't believe you can. 

My first audio interface, which I still have, but no longer use, is the earlier version - the UA-25, which is almost identical and I'm reasonably sure you have to pick one or the other, but not both. 

I think once that digital button is pressed, that's all you get.
 
The most you can record is one stereo pair input [L & R], or 2 single line inputs, [L & R], and I'm pretty sure that the digital in is considered a stereo pair, therefore counting as your 2 inputs right then & there, with no way to split them up.