How to Run 3.1 Servers under different account

I have waded through all the install PDFS, and still do not see this - how can I change the account that runs the different services?

In R2 you could change the account in the various services from Local System to another account, where is this done now?

Is this now just done in one place, the SIA, and ALL services run under this one account?

but in the ADMIN PDF, there's this on page 133

"In the CCM, select the node on which the servers runs, then update the password or account."

I see that there is an account here, but I cannot change it, and when I stop the node, then the whole page dies.

I need to run the CR job server with a single SQL account that has SELECT rights to the data.

TIA

Rick