Apple ID

See: What to do before you sell, give away, or trade in your iPhone, iPad, or iPod touch - Apple Support

Then set it up as new: Set up your iPhone, iPad, or iPod touch - Apple Support

If she is under 13, Help your child set up an iPhone, iPad, or iPod touch - Apple Support

and Family Sharing and Apple ID for your child - Apple Support

If not, How to create a new Apple ID - Apple Support

To change the Apple ID on the phone, you'll need to sign into your account. Are you having problems signing into the account? If yes, you'll need to recover your password. To do so,

Use If you forgot your Apple ID password https://support.apple.com/en-us/HT201487

If you cannot recover the password or equivalently cannot answer the related security questions successfully, then see: 

Security and your Apple ID https://support.apple.com/en-us/HT201303

This document says “without proof of your identity via security questions and other carefully selected criteria, Apple Support can't help you reset a password or perform any other actions on your account.” 

So, you will not be able to solve your problem unless there are extenuating circumstances. Still you can try to do so using the support options below. Be ready to provide any additional information to Apple you think may be pertinent e.g., the receipt for your purchase of the device with its serial number on it.

Get a call from Apple support to help solve your problem using this link https://getsupport.apple.com/?caller=kbase&PGF=PGF63005&category_id=SC0245&symptom_id=23362

Apple ID Support https://support.apple.com/apple-id

Apple ID account security for country-specific and region-specific help https://support.apple.com/en-us/HT204169

Get Support: We’re here to help  https://getsupport.apple.com/. Go through the options to find the best support option.

Did you do the steps in this article?

Selling/Giving Away Device.    

If 13 years old or older.

Apple ID - create a new.      

Apple ID – Create         

If under 13 years old, you will need to set up Family Sharing to create an ID.

Family Sharing and Apple ID for your child.      

Family Sharing.         

Family Sharing - Set up.        

How to switch Apple IDs on your iPhone or iPad.      

What to do after you change your Apple ID or password - Apple Support.