When you have the scope set at say 2 volts, is it only the software that is set to 2 volts and not the picoscope? By that I mean, you can sometimes get a bit of noise on the signal that can cause it to occasionaly spike above 2 volts, and get an exclamation mark on the screen.
If you set the screen on 2 volts it is not a problem if the spikes are higher then 2 volts. Just be sure that you stay under 100 volts. When you measure things like injectors or primary ingition, use the attentuators. The coils on these components produce high induction peaks when the current is cut off.