1- Open DSM Explorer and drill down to Control Panel --> Engines --> System Engine.
2- Right click the 'SystemEngine' and select create new instance.
3- Give the instance an appropriate name (in this example 'ReportEngine').
4- Open the command prompt and run the following commands:
caf setcreds ReportEngine user <domain\username> password <password>
5- Recycle the ReportEngine for the new credentials to take effect.
Note: This user account will be used by the engine instance 'ReportEngine' to write reports and needs to have Full Control permissions on the network share where the reports have to be written and to be a member of the local administrator group on the server where the engine is installed