Pro Sites: How to setup default theme for new signups?

Hi guys,

I'm a little confused .. maybe someone can help.

How do I setup a default theme for signup for new users using pro sites? I currently have one called headwaytheme which is great, but not when a new user signs up as there is some customisation required.

The strange thing is I must have been able to change the default theme at some stage coz its currently setup to one I setup.

Thanks .. I appreciate your help with this.

David