Usually sitting on the keyfob!, if you hold the unlock button (or sit on it) long enough all the windows will open (if it’s set in the cars system).
It’s happened to a lot of VW/Skodas, there’s an option in the car menu to turn the all windows setting on or off, it should be in the opening/closing section of the car menu.
Please excuse spelling/typos. Apart from being a clot it turns out I had one on my cerebellum that's now causing various problems!