Here's how you change the email address you use for your Apple ID:
1. Go to https://appleid.apple.com and sign in.
2. In the Sign-In and Security section, choose Apple ID.
3. Enter the email address that you want to use as your Apple ID.
4. Choose Change Apple ID.
5. If you changed your Apple ID to a third-party email address, check your email for a verification code, then enter the code. Learn what to do if you didn't get the email. --> If you didn't receive your verification or reset email - Apple Support
6. If you use services like iCloud or Messages to share with friends and colleagues, sign in to those services with your updated Apple ID. --> What to do after you change your Apple ID or password - Apple Support
For more details, read the document: "Change your Apple ID" --> Change your Apple ID - Apple Support
From what you say I am getting the impression you did not do it that way but instead created a brand new Apple account. All items downloaded with the old account are permanently tied to it. You will either need to revert to the old account (but you will not be able to use the email address you used for this new account), or delete the apps and download them with the new account, or set up Family Sharing with the old account.