Oracle: how to set only some roles as not default for a user (no GUI)
You have to use the GRANT command to grant roles (with admin option if required), then use ALTER USER to set roles to default (or not). So, the order of commands is,


grant roles (with admin option as needed)
alter user to set all roles to non-default
alter user to set only required roles to default.


A way to generate sql using sql is as follows, you can run this sql in instanceA, and actually execute the generated script in instanceB by replacing username if required. Make sure to test though,

with x as (select 'USER1' as usr from dual)
select cmd from (
select 1 as ord, 'grant ' || granted_role || ' to ' || grantee || case when admin_option = 'YES' then ' with admin option' end  || ';' as cmd
from dba_role_privs, x where grantee = x.usr 
union all
select distinct 2 as ord, 'alter user ' || grantee || ' default role none;' as cmd from dba_role_privs, x where grantee  = x.usr
union all
select 3 as ord, 'alter user ' || grantee || ' default role ' || granted_role || ';' as cmd from dba_role_privs, x where grantee  = x.usr and default_role = 'YES')
order by ord