Currently the form for creating forums does not explain where and how permissions are set. There is a field to "copy permissions from"; if a forum is chosen there that forum's permissions will be copied into the new forum, otherwise new forum will have no permissions.
I propose adding the following language to the instructions on top of the form:
"The new forum must have permissions set for users to see it. If you select a forum in "Copy permissions from" box below, that forum's permissions will be copied into the new forum. Otherwise the new forum will have no permissions and you will need to set them yourself. You will be able to set and modify permissions after you create the forum."
Furthermore, the notice that is displayed on successful forum creation is different depending on whether or not permissions were copied. If no permissions were copied, the notice includes a link for setting permissions. If permissions were copied, there is no link and it is not clear how to change permissions.
I propose always including the link to set permissions, possibly changing the label to: "You can set or change the forum's permissions here (link)."