Editing group permissions

We need to review and possibly edit some of our group permissions. We have
run a utility, recommended by help, that lists the security permissions and
the groups or users assigned to each permission. However, it seems there
used to be a way to list groups and users and the permissions assigned to
each group or user? We cannot find the listying by groups, is there a
utility or snap-in that we may have overlooked or need to load in order to
view and edit permissions by user or group?