How can I change the backup email to my security questions?

I've been having problems lately with my Apple ID, and I think if I figure out how to do this, it will be the answer to all of my problems. So back in 2013 I received an iPad mini for Christmas which had been my first Apple product, so I had to create an Apple ID. I made the Apple ID and everything worked fine, I'd just put in an alternate email for security questions that hides the characters so I have no idea what this email could be because I don't have it anymore. I got an iPhone 5S a year later in 2014 for Christmas, and I used the same Apple ID. I tried purchasing songs on the phone but iTunes had asked for verification through my security questions that I don't remember. I tried using the alternate email to get the answers but I didn't & don't have access, or even remember the alternate email. It was one I never used but probably made purposely for the Apple ID. So I had to continue purchasing everything through my iPad, and couldn't buy anything through my phone, (it's still that way.) The iPad mini cracked so bad that it started controlling itself, which made it almost impossible to use. It had & still has (because I still have it) a mind of its own, and does crazy things like types letters, opens apps, moves stuff around, etc. all by itself. I stopped using it and just bought a new iPad mini because around here it costed the same amount to get it fixed as it did for a new one I saw at Staples, so I just bought a new one because the other one is literally impossible to use. I still have all of these products, but I can't purchase anything off either of the new ones because it *** for verification that I can't provide because I don't know the answers to my security questions, or the email to get the answers. If anyone knows ANYTHING that relates to this or could help, or what you think I should do, please help. I've thought about just making a new Apple ID but I'm afraid I will lose all of the things I've already purchased. Thank you so, very much.

-Aria R.