I've run into a situation on several occasions where we've built a VDI collection, then due to some Active Directory housekeeping and changes, needed to edit the OU that VDI desktops get built in. For instance, when I created a collection, I wanted them built in:
But now I want them built in:
I looked at using the PowerShell command Set-RDVirtualDesktopCollectionConfiguration but there isn't an option to edit that according to the documentation for the command.
I found a way to do this using SQL and editing the Database.
Disclaimer: I'm assuming manually editing this DB is not officially supported by Microsoft. So this editing is done at your own risk. I tested this first on a test collection before changing anything in production. I suggest you do the same.
Using either SQL Server Mgmt Studio or your DB editor of choice, if you find the table called rds.VmProvisioning there is a field in the called UserGroupName that has the Active Directory Domain OU that your VDI desktops get built in. Just get the properties of your new OU using AD and going to the attributes and copying the distinguishedName value and pasting it into the field in the DB.
In order to get the changes to show up in Server Manager / RDS Management, I had to reload the entire Server Manager application. Once you do that though, your collection will now rebuild using the new OU.