The modelling / Librarian app is ToneX CS - not Amplitube, which is a standalone system that works with any audio interface.
In ToneX CS, when getting started with the One, I recommend you use the Librarian only and set the app's audio inputs to "None" in Settings. That way you can be sure you're hearing only the pedal, whatever you do. When you get better, you can try creating presets in the app, which requires the settings changes I've mentioned a few times already!
The factory bass presets are kind-of limited, but then you have loads of free community models through ToneNet. I'm trying out a JHS Colour Box model at the moment, which is a kind of vintage mixer channel that can be pushed in to distortion.
The ToneX CS interface is just bad, frankly. I'm getting better at it. When the pedal is connected, you have three sections on the right, top to bottom, and can drag & drop between them.
The pedal's slots (3 on the ToneX One).
The presets stored on the pedal (20 on the ToneX One)
The app's presets or tone models, depending on what you have selected in the left side column. It can be Presets or Tone Models, with a Preset being a Tone Model (stomp gain / amp / cab combo) plus the extra bits (gate, compression, effects etc.).
You filter the contents of the bottom box using the bottom left e.g. Bass for just bass presets, "Owned Only" to not show anything you don't already have. The Colour Box model was classed as "Owned" after I downloaded it to the app.