The three large buttons at the top front of the console pretty much control the different modes. Driving style, speed and traffic also have inputs. It's a pretty technical car designed to give decent performance while using very little to no gas. If you haven't done it, I highly suggest reading the owners manual. Your sales person didn't check you out on the car's operation and features??? If not, go back and ask for someone well versed on the car.
Welcome to the forum and congrats on the new car. If this is your first hybrid/ev there are going to be plenty of new features and driving characteristics to learn. The car will charge during use via regenerative braking, which is controlled through the paddles.
There are no stupid questions, there are only people too stupid to ask a question.
I just leave my car set to EV and so far I have used 0.04 gallons of gas in 2,000 miles.
The computer runs the ICE (ice = internal combustion engine) for a few seconds every week or two to keep the ICE lubricated. When the battery runs low (it keeps two bars in reserve) it automatically switches to ICE power.
The owner manual says to with to HV at high speeds but I don't think it is necessary and have not been give one reason why you can't just leave it in EV all the time. I am basing my opinion on driving 2,000 miles in my Honda and 3 years in a Chevy Volt