Try to recover access to the old account. If you cannot then you have lost access to items purchased with it and will have to buy them again with the new account. In general it is best to avoid creating a new Apple Account to avoid exactly this kind of issue.
This article tells you the various ways you can try to discover your forgotten Apple ID --> If you forgot your Apple ID - Apple Support Typically an Apple ID is an email address you have used. If you are currently using a mobile device that is logged into your account, go to Settings and tap your name at the top. Look in Keychain, and in a browser's security settings if you use it to automatically sign into Apple when using a browser.
This article outlines what to do If you forgot your Apple ID password --> If you forgot your Apple ID password - Apple Support
or go directly to this link --> http://iforgot.apple.com/
If you find you can’t sign in, reset your password, or receive verification codes, you can request account recovery (read this support article: How to use account recovery when you can’t reset your Apple ID password - Apple Support ) to regain access to your account. Account recovery might take a few days or longer, depending on the specific account information you can provide to verify your identity.
If you still need help this page provides country-specific Apple Support contact information ➞ Contact Apple for support and service - Apple Support
Once you have access to the old account you have to decide if you wish to even continue to use the new account. Not using it would be the easiest solution, otherwise you have to use Family Sharing to maintain usage of apps from the other account. To learn how to set up Family Sharing, read this support article --> Set up Family Sharing - Apple Support