Why do I have a capital gain carry over from last year. I didn't have a loss that I am aware of. How do I see where this comes from

Check your prior year Schedule D.   If your net capital loss was in excess of $3,000, that amount of loss will carryforward to 2020.

After you've checked your 2019 return and confirmed that should not have received the carryover. 

You can correct it on your 2020 tax return by:

1. Income
2. Scroll to Investment income
3. Select Capital loss Carryover
4. Make your correction.