SQL Server 2008: How do I change the default schema of the dbo?
Each database is owned by a server principal (aka login).  Inside that database, the owning principal is known as dbo (aka *D*ata*B*ase *O*wner).  The database principal (aka user) loses its real name.

For example, for a database I own:

select  [user].name as UserName -- Database specific
,       [login].name as LoginName -- Server wide
from    sys.databases d
join    sys.database_principals as [user]
on      [user].sid = d.owner_sid
join    sys.server_principals as [login]
on      [login].sid = d.owner_sid


Will print "dbo", "Andomar".  If you'd change the owner to sa:

exec sp_changedbowner 'sa'


The query would return "dbo", "sa".

You cannot modify the default schema for the user that owns a database.  It is always user name dbo with default schema name dbo.