Fish Demo Config Datablock

I've found that when I set up the config datablock for FishClass in the rollout in TGB, drag and drop a few animated fish and set their world limits (which should have been already set maybe???) they are not the same as the original fish. So I click on each new fish, change it's world limts to be outside the screen. I save, then run it, and they work fine, but when I get back to the level editor, sometimes the new fish lose their world limits - they get set to the default.

I tried saving, closing TGB and reopening, but the problem remains. Anyone know why?