I wanted to make arches for a car. I'm trying to cut the mesh verticaly (like on the second photo), but the knife doesn't snap to the verticles on the arches. Although, it does snap to verticles on the edges of the car. How can I snap the knife to the verticles? Thank you.
Is the curved edge part of the face? I do not think so, since the last vertex has no connection and an edge cannot simply stop in the middle of a face. So when you try to cut the face, the Knife tool only snaps to vertices that a part of a face which can be cut.
You have Snapping enabled (the magnet symbol), however the Knife tool does not use this. Snapping only works for transformations like moving, rotating or scaling.