Thanks for coming back with additional information, info4ruth1.
You can go back to your old expense entries individually and change the account to the new one. To achieve this, please follow the instructions below:
Learn more about managing expense transactions in QuickBooks Online (QBO): Enter, edit, or delete expenses in QuickBooks Online.
The Community is always open for follow-up questions and other concerns. Just leave me a reply below and I'll be sure to get back to you. Have a wonderful rest of the day!