Change the AOS service account

Hi,

I am trying to change the AOS service account because I don't want to let it run with the administrator account.

I tried this blog: http://blogs.msdn.com/b/axsupport/archive/2011/11/07/steps-to-change-the-aos-service-account-in-microsoft-dynamics-ax-2012.aspx

But I don't get step 2F. It asks for a TempDB but in the Ax configurator, I only configured two databases, just the database and the baseline database. So what do I need to fill in there?

When trying to start Ax, it's actually starting but it gives an error that the database does not exist.

Can anyone help me out? Thanks!