I found this small tutorial online : https://ccm.net/computing/hardware/403-qwerty-vs-azerty-keyboards/
There's a few steps, it involves going to the control panel, but it seems pretty easy to do. Although please don't bother too much if it doesn't work, and sorry for the lack of accessibility :( Thanks a lot for taking the time already.
(Also a quick thing that we forgot to put in the description : spells need to be unlocked, they won't work from the start. Unlocks disappear at the end of the wave (it's a bug) so don't forget to pick them up !)