Reseting my apple contacts.

Hey, I got an iPad air from my dad and made an apple account. While using Siri, I realized that my name is not set. So, I went to Siri settings, and clicked "My Info", but my dad's contact appeared.

How can I set My name at Siri?

The instruction told me to choose my name from the contacts.

Also, iMessage had the same result.

Note that, I logged out at my dad's iCloud, and setting.