If you bought the apps with a different ID they are permanently tied to that ID. You will have to delete the apps and re-purchase them with the new ID or try to remember the old ID and then set up Family Sharing with yourself.
Click on this link to read what to do "If you forgot your Apple ID password" - https://support.apple.com/HT201487
or go directly to this link --> http://iforgot.apple.com/
Also read about "What to do after [or before] you change your Apple ID email address or password" - https://support.apple.com/HT204071
If you still need help:
Contact Apple for help with Apple ID account security "This article provides country-specific Apple Support contact information for customers seeking help with their Apple ID password or other security-related issues." --> https://support.apple.com/HT204169
Set up Family Sharing - https://support.apple.com/HT201088