Design Specification Ventilation Design Flow Rate objects are a shared resource, but it is confusing, because unlike other shared resources, it doesn't show up in the internal load tab (like people, lights, etc).

The easiest way to make a unique instance is to drag on in from the library to the space or space type you want to change. Then You will have a unique rescue that you can rename and change characteristics for. For reference infiltration objects have similar but not exactly the same behavior.