The title already says it all.
How can I change the device? EDIT: Yes, I have a (Nvidia) graphics card and CUDA installed
I've got a GeForce GTX 960M with updated drivers
Additionally to installing the drivers and Cuda, I had to choose the NVidia card as the card used for rendering (hybrid card), by running
sudo prime-select nvidia and log off and in again, afterwards it works.
This is now really off-topic.