You can scroll vertically through your tracks in the Project Zone without clicking on the vertical slider. Just do this:
Hold the Alt key while moving your mouse wheel.
This does not seem to be mentioned in the Cubase 9.5 manual, so I hope this info saves somebody some time.
I don’t need to use the ALT key - in Windows just holding the mouse center button while dragging does this for me both horizontally and vertically.
btw putting your system details in your profile is helpful to see for issues like this. (Even if you’re humbled by the age of the system, as is my case 
)
You’re right, I don’t need the Alt key. The mouse wheel alone does it. Thanks for the tip. (Edit: My system details are now in my signature, as advised.)
I’d also like a keyboard shortcut to vertically zoom in on the audio waveform, but that seems to be impossible.