Problem with the knife tool.
I'm doing an exercise in affinity designer (a course from Ally) with that slice of pizza. If I have two overlapping lines like in the exercise and I want to cut away a part then I have no way to delete that one part, if I want to delete it then I also delete the part that I don't want to delete. It is very annoying because I cannot complete that exercise, but it is also very annoying with other design work. I have already tried all kinds of shortcuts, I have watched videos on the internet, it seems to work for everyone who has a Mac, but I have Windows 10 and it just won't work. Does anyone know how I should solve this? Thank you in advance.