I haven't got enough time on my vezel, it's just arrived a week earlier, but I figured out that there are 3 buttons under the steering. One say "SEL/RESET", the other two have up and down arrows on them. Push any of the up or down button and you will see different options on the screen. One of which is the fuel consumption. Now set your trip ODO meter through the SEL/Reset button, you can do this by continuously pressing the SEL button for 2 seconds when the ODO is on trip A, and it will be reset to zero.
As for changeover from hybrid to fuel, I normally judge that by the color of the meter, which turns BLUE in my car when it switches to petrol, and also through fuel consumption bars in the meter, which increases to almost 60km if the car is slow or running on cruise control. I hope this is helpful. For more, please watch this