Change user ID #1 primary group

[Tracy Perry]

Can UserID #1 primary group not be changed on a fresh install?  The only option for primary I have available is Administrator.  This was a conversion from myBB 1.8 -> IPB 3.4.7 -> IPS 4.

Am I missing a setting somewhere?  I'm wanting to keep the Administrator group as Administrator, but change my primary to Site Owner (which is a copy of the Administrator group).

[AutoItScript]

I can't change mine, so I guess not