I can’t change my alias back to msn.com

Please help.  I thought I'd check out the Alias option and created a new one.  I made it primary, but had no idea that it would not allow changing back from outlook.com to msn.com.  Another person emailed the exact same problem and someone sent a link to MSN that was useless.  Any suggestions are appreciated.  That site suggested changing my password, but it was a waste of time and solved nothing, other than creating potentially more problems.