Greetings,
My name is Rhaine, I'm an Independent Advisor and community member like you.
I am also using Office applications. Let us work together to sort this out.
First you need to deactivate the installation of Office in the pc you sold.
Go to this link below.
https://www.office.com/myaccount
Sign in with email address associated with that account.
Under Devices, select Sign out of Office next to the device.
It can take up to 72 hours for Office to detect that you signed out remotely.
If you want to install in your new device
Sign in to the same link and click install under services and subscription.
https://www.office.com/myaccount
I hope the information above helps. Please let me know if you have further questions.
Have a wonderful day ahead and stay safe.
With Warm Regards,
Rhaine C.