Help - I have email ending in @me.com. I have an Alternate email that ends in @icloud and goes to my @me.com email address. I need all my outgoing mail to go from the @icloud.com address. I've searched for hours. How can I do this?

Help - I have email ending in @me.com. I have an Alternate email that ends in @icloud and goes to my @me.com email address. I need all my outgoing mail to go from the @icloud.com address. I've searched for hours. How can I do this?

I've searched and it says to simply select the @icloud.com account, but that option is not available. It seems as though apple views me as only having the @me account for email. Increasingly people no longer recognize @me accounts. I tried creating the new @icloud.com account and it says it already exists as an alternate email so it won't allow creation.