Why it doesn't work
000000000000000000000000Steward1 is seed which (given default key derivation method) generates DID Th7MpTaRZVRYnPiabds81Y. You can verify yourself using indy-cli (command line tool)
indy> wallet create test key=123
Wallet "test" has been created
indy> wallet open test key=123
Wallet "test" has been opened
wallet(test):indy> did new seed=000000000000000000000000Steward1
Did "Th7MpTaRZVRYnPiabds81Y" has been created with "~7TYfekw4GUagBnBVCqPjiC" verkey
In the network you are using, the owner of DID VsKV7grR1BUE29mG2Fm2kX (ie. whoever has knowledge about its associated private key or seed) has steward role which grants permissions to do various operations on the ledger. So if you modify the seed, it will generate different DID which won't have required permissions to execute operations used further in the tutorial (like writing data on the ledger).
Where is 000000000000000000000000Steward1 coming from
From what you say I presume you are using prebuilt docker image from indy-sdk repo running pool of indy-node instances in it, following some of these instructions.
So the simple answer is that configuration for 000000000000000000000000Steward1 is pre-baked in it. Look at the dockerfile used for building indy-pool image. Notice these lines
RUN awk '{if (index($1, "NETWORK_NAME") != 0) {print("NETWORK_NAME = \"sandbox\"")} else print($0)}' /etc/indy/indy_config.py> /tmp/indy_config.py
RUN mv /tmp/indy_config.py /etc/indy/indy_config.py
Let's look what's in these files
docker exec indylocalhost cat '/etc/indy/indy_config.py'
# Current network
# Disable stdout logging
enableStdOutLogging = False
# Directory to store ledger.
LEDGER_DIR = '/var/lib/indy'
# Directory to store logs.
LOG_DIR = '/var/log/indy'
# Directory to store keys.
KEYS_DIR = '/var/lib/indy'
# Directory to store genesis transactions files.
GENESIS_DIR = '/var/lib/indy'
# Directory to store backups.
BACKUP_DIR = '/var/lib/indy/backup'
# Directory to store plugins.
PLUGINS_DIR = '/var/lib/indy/plugins'
# Directory to store node info.
NODE_INFO_DIR = '/var/lib/indy'
NETWORK_NAME = 'sandbox'%
This
# Directory to store genesis transactions files.
GENESIS_DIR = '/var/lib/indy'
Looks like what we are looking for. Let's see what's there
docker exec indylocalhost ls '/var/lib/indy/sandbox'
data
domain_transactions_genesis
keys
node1_additional_info.json
node1_info.json
node1_version_info.json
node2_additional_info.json
node2_info.json
node2_version_info.json
node3_additional_info.json
node3_info.json
node3_version_info.json
node4_additional_info.json
node4_info.json
node4_version_info.json
pool_transactions_genesis
In blockchains, genesis file is typically the file you use to initially kick off the network and may populate network with some data. In case of hyperledger-indy, there's 4 "subledgers" which contain different types of transactions: domain, pool, config, audit. The domain subledger is the one which contains things such like DIDs, credential schema or credential definitons. We are looking for a DID, so let's look at file domain genesis file.
docker exec indylocalhost cat '/var/lib/indy/sandbox/domain_transactions_genesis'
{"reqSignature":{},"txn":{"data":{"dest":"V4SGRU86Z58d6TV7PBUe6f","role":"0","verkey":"~CoRER63DVYnWZtK8uAzNbx"},"metadata":{},"type":"1"},"txnMetadata":{"seqNo":1},"ver":"1"}
{"reqSignature":{},"txn":{"data":{"dest":"Th7MpTaRZVRYnPiabds81Y","role":"2","verkey":"~7TYfekw4GUagBnBVCqPjiC"},"metadata":{"from":"V4SGRU86Z58d6TV7PBUe6f"},"type":"1"},"txnMetadata":{"seqNo":2},"ver":"1"}
{"reqSignature":{},"txn":{"data":{"dest":"EbP4aYNeTHL6q385GuVpRV","role":"2","verkey":"~RHGNtfvkgPEUQzQNtNxLNu"},"metadata":{"from":"V4SGRU86Z58d6TV7PBUe6f"},"type":"1"},"txnMetadata":{"seqNo":3},"ver":"1"}
{"reqSignature":{},"txn":{"data":{"dest":"4cU41vWW82ArfxJxHkzXPG","role":"2","verkey":"~EMoPA6HrpiExVihsVfxD3H"},"metadata":{"from":"V4SGRU86Z58d6TV7PBUe6f"},"type":"1"},"txnMetadata":{"seqNo":4},"ver":"1"}
{"reqSignature":{},"txn":{"data":{"dest":"TWwCRQRZ2ZHMJFn9TzLp7W","role":"2","verkey":"~UhP7K35SAXbix1kCQV4Upx"},"metadata":{"from":"V4SGRU86Z58d6TV7PBUe6f"},"type":"1"},"txnMetadata":{"seqNo":5},"ver":"1"}
{"reqSignature":{},"txn":{"data":{"dest":"7JhapNNMLnwkbiC2ZmPZSE","verkey":"~LgpYPrzkB6awcHMTPZ9TVn"},"metadata":{"from":"V4SGRU86Z58d6TV7PBUe6f"},"type":"1"},"txnMetadata":{"seqNo":6},"ver":"1"}
{"reqSignature":{},"txn":{"data":{"dest":"MEPecrczs4Wh6FA12u519D","verkey":"~A4rMgHYboWYS1DXibCgo9W"},"metadata":{"from":"V4SGRU86Z58d6TV7PBUe6f"},"type":"1"},"txnMetadata":{"seqNo":7},"ver":"1"}
{"reqSignature":{},"txn":{"data":{"dest":"EAPtwgevBpzP8hkj9sxuzy","verkey":"~gmzSzu3feXC6g2djF7ar4"},"metadata":{"from":"V4SGRU86Z58d6TV7PBUe6f"},"type":"1"},"txnMetadata":{"seqNo":8},"ver":"1"}
{"reqSignature":{},"txn":{"data":{"dest":"LuL1HK1sDruwkfm68jrVfD","verkey":"~Nyv9BKUJuvjgMbfbwk8CFD"},"metadata":{"from":"V4SGRU86Z58d6TV7PBUe6f"},"type":"1"},"txnMetadata":{"seqNo":9},"ver":"1"}
{"reqSignature":{},"txn":{"data":{"dest":"462p8mtcX6jpa9ky565YEL","verkey":"~LCgq4hnSvMvB8nKd9vgsTD"},"metadata":{"from":"V4SGRU86Z58d6TV7PBUe6f"},"type":"1"},"txnMetadata":{"seqNo":10},"ver":"1"}
And you can see that DID Th7MpTaRZVRYnPiabds81Y is hardcoded on this ledger using verkey ~7TYfekw4GUagBnBVCqPjiC which is matching what we've generated from seed 000000000000000000000000Steward1. You can also see it's given role "2". If you dig deeper, you can find in indy-plenum, the consensus alg. project used by indy that role ID 2 is steward role.
