Change SharePoint Service Account using PowerShell

Question

In the Central Admin you are able to change a registered Service Account to a specified service (as in the image)

Is this possible to manage by PowerShell?

Answer 1

To set the account associated with a particular Service Instance using Windows PowerShell we simply get the ProcessIdentity property of the Service Instance and set its Username property. Once set we call Update() to update the Configuration Database and then Deploy() to push the change out to all Service Instances.

$pi = $svc.Service.ProcessIdentity 
if ($pi.Username-ne $username) { 
   $pi.Username= $username 
   $pi.Update() 
   $pi.Deploy() 
 } 

http://blog.falchionconsulting.com/index.php/2010/10/service-accounts-and-managed-service-accounts-in-sharepoint-2010/