When I press C4 (“Middle C”) on my 88 key keyboard, the highlighted note on the Key Editor’s vertical keyboard is called “C3”. So it appears Cubase is an octave off with its note naming. The note I played sounds a C4 alright (checked it with a hertz meter).
How can this be corrected?
Different systems (nationalities?) use a different notation for Middle-C.
I wish they would all standardize on the MIDI number and refer to it as C 60. It would at least make finding Middle C easier. 
Didn’t know that. Thought C4 for middle C was universal (IPN, International Pitch Notation). You would expect Cubase to follow that notation. Strange. Can it be changed?
This can’t be changed in the current version, sorry.
There’s no “correct” number for middle C. Middle C being C4 is mainly an american thing. Most other countries call middle C “C3”, including important markets for Steinberg such as Japan and Germany.
The only “correct number” for Middle C would be the number that a Cubase user is used to. So it baffles me that Cubase doesn’t allow you to change this in “Preferences”.
And some music software vendors call middle C “C5”. There’s some merit to this. Middle C (MIDI note 60) is five octaves above MIDI note 0. Everyone should just universally use MIDI note numbers instead and this problem would disappear.