Using QuickBooks Plus online and I entered Jan 1 2021 and I wanted it Jan 1 2020. How do I change this date?

Hello there, @soleiltan2.

Based on your description of the issue above, it seems like you want to change the date range of the downloaded bank transactions in QuickBooks Online (QBO). Currently, when you connect your bank or credit card accounts to QBO, you can usually download the last 90 days of transactions (others can go back as far as 24 months depending on the financial institution). Then, changing the transaction's date isn't an option.  

However, you can manually import your data starting January 1, 2020. This way, you can keep your transactions updated. This will be a two-way process wherein you'll first need to manually download your transactions from your bank before you can upload them to QBO. For the step-by-step guide, I'd recommend checking out this article: Manually upload transactions into QuickBooks Online. 

Once uploaded, you'll have to review and/or match your transactions to the existing entries in QuickBooks. This is to keep your financial data accurate. You can refer to this article for the detailed steps: Categorize and match online bank transactions in QuickBooks Online. Then, I'd recommend reconciling your accounts every month. With this, you can effectively monitor your income, expenses, and the growth of your business. 

Don't hesitate to leave a comment below if you have other concerns about managing your online banking transactions in QBO. I'll gladly help. Keep safe always.