Host management credentials greyed out VMM

Question

Hello,
I am trying to add a file share storage to our cluster in VMM. But when doing that it gives an error saying "No Run As account is associated with the host. You have not specified a Run As account for your host."
Some googling on that issue points me to add "Host Access" on each specific host, so far so good.
But in order to do that I go to properties on a host and select "Host Access" but the "Run As account"-field is greyed out. Why is that? I cant find a single similar case when googling which leaves me out of ideas.
So anyone with an idea why this field is greyed out?
We are running a 4 node Hyper-V cluster and have just set up VMM, the VMM is running on the cluster - I hope this won't cause any issues.

Answer 1

Kristian: I admire your knowledge. But I think you are wrong this time.
You can update the credentials in a running cluster without removing it from VMM.
 Why it´s grayed out I leave to someone at MSFT to answer.
A little bit of this:
http://technet.microsoft.com/en-us/library/hh801619.aspx
and a little bit of this:
http://technet.microsoft.com/en-us/library/hh801522.aspx
Can result in something like this:
$YourCluster
= Get-SCVMHostCluster
-Name YOUR-CLUSTER-NAME
$YourRunAs
= Get-SCRunAsAccount
-Name "YOURRUNASACCOUNT"
Set-SCVmHostCluster
-VMHostCluster $YourCluster
-VMHostManagementCredential
$YourRunAs
This one works like a charm for VMM 2012 SP1 for Windows 2008 R2 and 2012 clusters.
Do you want to update the old threads related to the same subject or do you want me to do it? ;)