How to start over my cash flow at the beginning of the year

Hello, Carpentersunite. 

I understand you want to change the account balance to zero for the cash flow from the previous year in QuickBooks Online. If you have entered an opening or beginning balance in your account, you must edit it manually.

However, if you have not entered an opening or beginning balance, you can Undo it and then Exclude the transaction from the previous year. Once all the previous year's transactions are excluded, QuickBooks Online will reset the account balance. After this, you can start tracking transactions for the current year. 
  

To do this, Go to the Transactions tab and select Bank transactions. Then, choose the bank account, and from the Categorized tab, click Undo. This will be removed from the categorized tab and moved to the For review tab.  

From the For review tab, mark checks all the boxes that you want to exclude the transaction and select Exclude.

For more details, check this article: Exclude a bank transaction you downloaded into QuickBooks Online.

Once everything is set, I suggest reconciling your account so everything stays balanced.

Please let me know if there's anything else you'd like to take care of in QuickBooks Online. I'm ready to help you with your transactions, reports, and other processes. Just reply here, and I'll reply as soon as possible. Have a great day!