Hmmm no that button doesn't exist for me. I see the User ID field, but that's not really user friendly for my setup:
The way I've got it setup is I have for instance 100 categories.
For each category I have a user group, again 100. It's not very efficient having to setup both a group and category, but the reason it's like this is because then when I create a new user all I have to do is tick each user group that they belong to, which are all in a list. Under permissions for the category, I just have 'download' set to allow for the equivalent user group. Unfortunately Joomla doesn't seem to have a 'view' permission.
So they may belong to 30 different groups, of which I can tick all at once on the user screen. Doing it your way, I have to manually open 30 different categories adding them individually to each category, which is very time consuming when you have 100's of users.
The problem is while the user can't download any files in any category they don't have permission for, they CAN still view the category and file names. I need these to be hidden.
Is that possible? If not, how much would it cost to make it possible?
Or doing it a different way, could there instead be Users tab under edocman where each user has a page that lists all the categories they belong to, exactly the same way the built in Joomla users page does it with user groups (and how much would that cost?). That way I could do away with all the user groups.