Thanks @Nathan Explosion and @Marc Stridgen, I was doing it this way. It is forum by forum for me because I need check or uncheck one by one for every, Group (4), forum (300) and situation (5), see, read, post, reply and download.
To simplify, I've this forum structure and I need this permissions:
Category 1 to 5: Forum 1 to 25 and every forum have 20 subforums (For every category)
Group 1 to 4
Group 1: can see all categories, forums and subforums (it is easy, only need check one column field), Category 1 Forum 1 to 5 with all subforums can read, post, reply and download.
Group 2: Group 1 permissions plus Category 1 Forum 6 to 15, Category 2 Forum 1 to 5, Category 3 Forum 15 to 20 with all subforums can read, post, reply and download.
......
Group 4: can read, post, reply and download all categories, forums and subforums. (It is easy too)
Can you imagine the complexity?
I can't set permissions for all subforums in a forum by one click, I need a lot of clicks. The same for categories. It is necessary to be able to set these permissions by forum and category grouping.
In fact, setting permissions with the checkbox in the top column only makes sense for the Administrator or Moderator, other groups will always need a more varied combination and is not easy to do.