Most rear-wheel-drive cars tend to be over-steery, and most drivers prefer them that way. Most front-wheel-drive cars tend to be under-steery. Lately, some newer rear-wheel-drive cars are tuned at the factory for slight understeer in many cases because it's safer for a novice driver (controlling/recovering from understeer is more instinctual without training and practice). Our Z's are in this category: they are a rear-wheel-drive car, but they have some gentle understeer tendencies unless you really stomp it at the wrong time (at which point VDC will probably kick in, slow you down, and make a mess of everything). With VDC off you can still push yourself into oversteer in a low-speed corner with the throttle pretty easy though.
All of those nuances aside though: unless the car's setup is way out of whack, it's really up to the driver to manage the rest. You might want to make setup changes to change the nature of the car and make it feel more natural to you, but the bottom line is it's on you to control the rear end of the car with throttle and steering inputs. It takes a lot of practice. Personally, I wouldn't go after switching to a square wheel setup just to try to address this issue (which it wouldn't do anyways I don't think) - I'd focus on training yourself instead. Learn to predict better, react better, use smooth-but-fast precise inputs to the throttle and steering, etc. If you get good enough at that stuff, any actual setup problem in the car will just be an annoyance, but not a dangerous hinderance.
TL;DR - Sign up for a DE or Auto-X event near you ASAP
Experimenting with a car you can't control on the street is dangerous.