How to Change Office Professional 2019 Product Key?
1) Open Word, close the activation window, click Blank document, Click File and then click Account.
2) If you’re signed in, select Use a different account, and then select Enter product key instead.
3) If logged in already, click “use another account”. Then under signin button, you should see a link “Enter Product Key instead” or “continue without signing in”. Click on that link and enter the new product key.
4) Then click activate.
5) Once activated, close Word and open again to make sure it’s activated.