lentrea,
Hmm, something seems incorrect. Are you logged into the phone with your Apple ID? Go to Settings > your-name > "Name, Phone Numbers, Email." Does your information show? If that is correct, see this:
Change or remove your Apple ID payment information
If you are still having issues, and the previous owner is available, work with them to do this:
What to do before you sell or give away your iPhone, iPad, or iPod touch
Good luck.