How do I go back to match bills from POs to payments that I accepted in banking?

Hi info62,

You can undo the transactions accepted from the banking section, and match them again by following these steps:

1. On the left panel, click Banking.
2. Click the In QuickBooks tab.
3. Find the transactions you accepted and click the Undo link under the Action column.

Once done, go back to the For Review tab, and click the Match link or Find Match.

You can also check this article for more information: How to Add and Match Downloaded Banking Transactions.

I'll be around if you need more help with QuickBooks. Thanks.