How do I register my all in one 21 when I already registered my all in one 16

[MomOfTeb]

I purchased an HP All-in-One - 21-2019 + I already owned an all-in-one 16 and believe I have an account with HP. I was so happy with it that

1.  I purchased another one but it is an all-in-one 21 and has been in the box until 2 weeks ago when we were able to get it and use at our daughters where there is wifi.

2.  I have been trying to register it but keep getting a message saying everything has expired and no longer in effect even though I never registered this new one. It may be a confusion of me already having an account from the 16 inch model.

3.  Even the McAfee has expired so I am trying to find the free windows virus protection to install and malware program but not sure and will wait until you get back to me.

4.  I also noticed that I made a typing error on my screen name....it should be MomOfTen and I don't know how to change or reset it.  

If someone would could please  help me with these problems I would appreciate it as I am a senior and this is all so overwhelming and confusing.

[WAWood]

@MomOfTeb 

The warranty date is set at the factory when the PC is built, so it starts expiring immediately.  Even though you purchased it some time ago, that date never got reset -- and I don't think you can now do that yourself, online.

You will need to contact HP Customer Support and get their assistance in this.

If you live in the US or Canada, contact information is on this page: http://www8.hp.com/us/en/contact-hp/phone-assist.html#section1

If you live elsewhere, contact information is on this page: http://www8.hp.com/us/en/contact-hp/ww-contact-us.html

NOTE: After you get through, stay on the line until you are finally able to talk to some one -- it can take a while!

If you have trouble finding a phone number, then try: 1 (650) 857-1501.