It’s easy. First you click here:
Then you find the SQL Server 2008 or 2008 R2 program group
Open those and then pick the SQL Server Configuration Manager.
You might get a UAC message asking if you want to make changes to the system, and say yes. This application can change service accounts, which is a sysadmin function. The screen basically looks like this:
If you right click the SQL Server entry, the database engine, you can select the properties, and you’ll get this screen:
On this screen, you can change the service account, and this is where you should change it. There are the three built in accounts in the top drop down (Local System, Local Service, and Network Service). I don’t recommend these. Instead, I recommend you create a new Active Directory Domain account (or local user account), assign it no rights, and then use the lower radio button to select the account.
Note that you do can search for it, and also you need to enter the user account. The password, while conforming to your domain policy, shouldn’t be one you use elsewhere. Make it a long, impossible to guess combination of stuff. You don’t need to recover this or log on as the user after you’ve assigned it to SQL Server. If you need to recover the password, just change it.
A couple quick notes, on the Service Tab you can set the startup mode (Manual, automatic) for the database engine.
You can also change startup parameters here, on the Advanced tab.
That’s it, it’s easy, and it’s how you should change the service account for SQL Server.