Hide on screen values will only be effective for the first field group loaded. This load order is set by the “Order No.” value of the field group.
Description is only shown on the ACF admin.
How are your field groups added? Are they only in the admin or are they added using PHP?
WP remembers the order that the field groups were displayed and shows them in that order, even when you later change that order in the field group settings. These values are stored in the _usermeta table per user per screen, the order of meta boxes on the post screen for example are stored with the _usermata meta_key of “meta-box-order_post”. As far as I know, the only way to clear reset this is to go into the database and delete it. I did locate some code that might allow you to set the order here http://wordpress.stackexchange.com/questions/15376/how-to-set-default-screen-options
