Try the directions in the article If you forgot the answers to your Apple ID security questions - Apple Support for resetting your security questions:
"Reset your security questions
1. Go to https://iforgot.apple.com/ .
2. Enter your Apple ID, then select Continue.
3. Choose the option to reset your security questions, then select Continue.
4. Enter your Apple ID password, then select Continue.
5. Follow the onscreen steps to verify your identity. The information you’re asked to provide may vary based on your account details and other factors. If you don't get any options to verify your identity, you can't reset your security questions at this time.
6. Choose new security questions and answers and select Continue."
If you get a message about not having 'sufficient information', you will not be able to reset your security questions.* Several years ago Apple transitioned to using to two factor authentication instead of security questions and has been encouraging users to switch to the newer security system. Your next recourse will be try to change to two factor authentication as outlined in this article --> Two-factor authentication for Apple ID - Apple Support Follow the instructions in the section "Turn on two-factor authentication for your Apple ID"
If you wish to speak with Apple about this, contact with Apple ID account security using the information in this document --> Contact Apple for help with Apple ID account security - Apple Support
*Dec. 2022 post by Apple Community Specialist K_Faith in the thread I’ve tried resetting my security question… - Apple Community
"If you’ve forgotten your security questions, there isn’t a way for Apple to reset them for you, or another way to access your account. You would need to create a new Apple ID, which also means you won’t have access to previous purchases or data stored in iCloud."
Part two is forgetting about the old ID and get the iPad working, period. Apple has two related features, Activation Lock ( Activation Lock for iPhone, iPad, and iPod touch - Apple Support ) and Find My ( iCloud+ - Find My - Apple ), which are designed to prevent anyone else from using an iPhone, iPad, or iPod touch if it's ever lost or stolen. Deactivation of either requires knowing the Apple ID and password that set the feature, or by placing a special request to Apple to reset the device. This Apple ID information essentially defines the current ownership of the device. Unless you can get the account working again, your only option is to hope the receipt for purchase of the device can still be found. Apple can completely reset a device if a person can provide sufficient evidence of valid ownership. This is done online at: Activation Lock support request - https://al-support.apple.com/#/additional-support Apple says, "Proof of ownership documentation is required," but does not provide many details in the article as to what is acceptable proof. Prior to this official service Apple typically required the original receipt* issued by Apple or an Apple Authorized Reseller and documented provenance (so typically it would be the first owner who does this, or a descendant with legal proof of ownership transfer).
*Apple recommends you keep your receipt after you buy an Apple device. --> Keep your receipt after you buy an Apple device - Apple Support
