Make sure that you are running the game update and pressing the large green "Update/Restart" button at the bottom of the panel when you first rent a server. This will install all files needed for the first boot.
You want to be certain that you stop the server before editing, make the edits, save the changes, then start the server up using the "Start" button in the top right corner of the control panel.
You should be able to edit this setting, and any other dinos settings in the Dinosaur Config section of the Modify Config Tool in your server control panel.