The mqsichangedbimgr command updates the Windows service that runs the Derby Network Server, with a new user password, a new user ID, or both.
If you use the unqualified form for this user ID (username) on Windows systems, the operating system searches for the user ID throughout its domain, starting with the local system. This search might take some time to complete. The ServiceUserID specified must be a member of the local group mqbrkrs. On Windows systems, it can be a direct or indirect member of the group. The ServiceUserID must also be authorized to access the home directory (where WebSphere Message Broker has been installed). The security requirements for the ServiceUserID are detailed in Security requirements for Windows platforms.
The user ID used to invoke this command must have Administrator authority on the local system and be part of the mqbrkrs group.