I have a control Panel at http://access.enom.com But I can't changed my name servers. Exam when I entered:
1/ ns1.mynameserver.com
2/ ns2.mynameserver.com
But they always change their places to:
1/ ns2.mynameserver.com
2/ ns1.mynameserver.com
Please help me.

I think you should wait 24 hours to check the change.