Yes that's how it's supposed to work. Those permissions allow a roles users to perform those actions across the entire forum. Useful for admin/moderator-like roles without access to the admin dashboard.
I've already said however that I will add extra permissions for individual roles such as "can edit own topics/posts" and then you would need to make sure that that roles edit permission in the forum(s) is unchecked. This will be in the next version.