HI Patricia,
Now to make sure that we are on the same page, as long as you have followed the steps from the original article that you came from then you should be good. Those steps were to sign out of iTunes with the AOL account and then sign back in to walk you through converting it to an email address as the username. As long as when looking at your Apple ID that is signed into iTunes, you see an email address then you have made the change. If you are still stuck then I would recommend that you contact Apple before the deadline of March 31st so you will not have any issues.
Contact Apple Support
https://getsupport.apple.com/GetproductgroupList.action
Take it easy,
-Norm G.