Thanks! So i suppose that there isn't a way to zoom with the scope running...
Without running afoul of the possibility of opamp saturation and other such issues? No, not to my knowledge. And that's because the knob controls both the interpretation of the ADC output for display purposes
and the signal gain. Which is almost always exactly what you want, really, because the purpose isn't just to show a different part of the waveform, but to show that part with as much resolution as the scope can bring to bear. The latter requires changing the amplifier gain and offset so that what gets fed to the ADC meets its input requirements in such a way that its output has maximum resolution over the voltage range that would be visible on the display at that setting.
For instance, let's say that you've got the scope set up to display 4.0V to 4.8V, at 0.1V/div. That means that the voltage fed to the ADC would have to be shifted so that 4.0V on the scope input would wind up being 0V at the ADC, and 4.8V on the scope input would wind up being whatever voltage the ADC would translate to its maximum converted value. If the input voltage range of the ADC is 0V to 1V, then after subtracting 4.0V from the input, the remaining signal would have to be amplified via a gain of (1.0V/0.8V = 1.25).
The above is, of course, a significant oversimplification (in reality, things seem to be arranged so that some of the waveform can extend beyond the screen edges, and there are likely many other considerations on top of that), and there are probably papers that rf-loop and others here can point at which would describe in detail the process that modern DSOs use to translate an incoming signal to something on the screen, but it should at least answer the question of why your vertical settings matter for things like the internal signal amplification.
You can see this in action by significantly decreasing the V/div so that the waveform in full extends well above and below the edges of the screen, then stop the scope, and then increase V/div. There will be a bit of waveform that extended past the edges of the screen, but not terribly much.