What account are you logging into e.g. are you using an email address to log in '...@aol.com'), to just an AOL username ('...' without the '@aol.com') ?
Email address iTunes accounts ('...@aol.com') are not affected - you don't have to do anything to that account. The only accounts that are affected are AOL username iTunes accounts e.g. if what you are using to log into iTunes is without the '@aol.com' at the end of it.
If you have used your AOL username with iTunes in the past and you have any purchases and/or a balance on the account that you want to have access on after the end of March, then you have to convert it to be an email address instead : Convert your AOL Username to an Apple ID - Apple Support
If you do need to convert an account then you can't use an email address that is already being used as an account's primary email address - so if you also have an account that uses your @aol.com email address then you won't be able to put that address on the AOL username.