this is not an issue of the announcements module.
You can set folder permissions to everyone for all folders in your filesystem through an sql script though:
declare @PermissionID int
select @PermissionID = PermissionID from {objectQualifier}Permission where PermissionCode = 'SYSTEM_FOLDER' and PermissionKey='READ'
declare @FolderID int
DECLARE FoldersCursor CURSOR FOR
Select FolderID from {objectQualifier}Folders
OPEN FoldersCursor
FETCH NEXT FROM FoldersCursor
into @FolderID
WHILE @@FETCH_STATUS = 0
BEGIN
if not exists (select * from {objectQualifier}FolderPermission where (PermissionID = @PermissionID) and (FolderID = @FolderID) and (RoleID=-1))
begin
insert into {objectQualifier}FolderPermission (FolderID, PermissionID, RoleID, AllowAccess) values (@FolderID, @PermissionID, -1, 1)
end
FETCH NEXT FROM FoldersCursor
into @FolderID
END
CLOSE FoldersCursor
DEALLOCATE FoldersCursor
Run this script from host > sql, and all your folders, in all your portals will have read permissions for all users set.