Currently, there is only one real way that might save time. If you have many forums that need to have their permissions changed to the same permission set, then what you could do is:
Modify the "New Forum Template" in the permission editor. At that point, you could bring up each forum, and then just choose the copy option to copy the New Forum Template permissions, and then update it.
Definitely need to spend more time in this area to make it easier to edit permissions on a larger scale.