I'm a bit confused about the user-seed.conf. Based on the documentation provided by Splunk, it seems this is to set up the initial password. Does this apply to Splunk universal forwarders? I am using the Splunk Enterprise version, and when I got to log into the web portion, I do change the default admin password. Do I still need to create a user-seed.conf file and then drop different credentials in there? Splunk doesn't really provide a good context for what this is used for in my opinion.
I am not sure I understand what you mean. Changing the password of the deployment server or the indexer has no effect on the password of any forwarder.
You must change the password on each splunk instance. If you are not going to change the password on the forwarder, then you should use the user-seed.conf file. It is not encrypted, so the password will appear in clear text. That's pretty lame but I guess it beats leaving the password set to changeme