Service settings allow you to set what user account on the computer the service should run as. Typically, the service will run as the local system account user. However, in some situations it may be necessary for the service to run as some user other than the this one. Generally this will be because the file is either accessing files (log files, for example) or writing files (datasets) to directories to which the system account user does not have appropriate privileges. A typical scenario would be saving a dataset to a network address for which the local system account does not have write privileges.
