Hi Hyacinthclare

I noticed this year in QBO 1099 preparation that the process seems to jump ahead. If you look to the left, you will see a vertical bar of circles with numbers in them. You are on the Proceed to 1099 bubble. That is several steps down. If you look to the lower left, you will see that you have the option to go back. Click back until you come to the account assignment. You can then fix your issue and then move forward. 
I hope this helps.