The code will depend entirely on the data feed you are using, not the software. The code for myTrack is completely different to the one for IB, etc. Which one are you using?
And are you sure you mean December? December has just expired, and the quarterly contract now being traded is March, which has the code H.
So if Q`Z is for December, Q`H will be for March. Remember that the ` is to the left of the number 1 on the keyboard, not an apostrophe which is '. This is a quirk of myTrack.