How to edit settings of Dynamics 365 Trial instance

I’ve added a Trial instance of Dynamics 365 version 9.0 to our tenant. Our company name was copied to the instance name and to the URL with an extra ‘0’ to make it unique.

But when I connected to our production instance (with the same name) from XrmToolBox I got connected to the Trial. What the flow?
OK, that must be because of the same instance name so let’s change that. Oh no, that’s not possible through the UI.

Wait, if I take a look at the URL when I edit the settings of the production instance, I might be able to construct the URL for the Trial instance:
https://port.crm4.dynamics.com/G/Instances/RetrieveInstanceSettings.aspx?OrganizationId=guid&IsFirstRun=false&IsConfigMode=false&selectedRowIndex=number

So when I choose the Notifications option at the Trial instance, I can get the guid from the URL and use that in the previous one. And that worked.

So I could change the instance name and URL, and also set the Security Group to restrict access to the Trial instance or else all these promo apps will show up for all users and that might scare them.