So, you need to set this for each creature.
Added after 36 seconds
They have personal checkboxes.
But does that mean you can't set it for everyone at once?:(
Added after 6 minutes
The number set on the map is correct for the warrior. The coefficient is 0.5 for the recruit, about 1.39 for the veteran, and 1.5 or 1.6 for the hero.
In the map properties tree, in the objectives branch, there are flags for this (they have quite descriptive names, it's hard to miss). Separately for each player, and it seems there's also a general one.