I'm not sure if I understand the difference? If you are changing the label you need to change it on all of the search heads in the SHC in addition to having it consistent on the Deployer. A word of caution on 6.3.2, please ensure you have the config correct for the ./splunk init shcluster-config command - I had to re-configure the entire cluster to get this functioning properly. Additionally you will want to try to avoid using a "$" in the secret as when I got around to installing apps this appeared to cause issues in the CLI.
So that's the question - do it to a single member of the cluster, or do it to every member (plus the deployer, as you point out). You are saying you must do it to every member, but the doc shows it both ways. So if you're right, we need to change one of the docs.