Configuring inputs.conf to send data to specific Index

I have a Splunk setup defined like: Universal Forwarder ---->Heavy Forwarder ------>Indexer I need that all the logs hitting my Indexer should go to specific index. Which option is better: 1) Configuring **index= new_index** in Universal forwarder's input.conf 2) Configuring **index= new_index** in Heavy forwarder's input.conf 3) Configuring **index= new_index** in Indexer's input.conf