How do I add an existing account to an existing budget?

Hi there, Pablocruz.

When an account is already created in the Chart of Accounts, it will automatically show up on the budget page. Note: The accounts that will show up on the page depends on the Budget Type (Profit and Loss or Balance Sheet) you have selected.

We have the Profit and Loss which reflects all activity for your income and expenses, and the Balance Sheet that produces the assets, business's equity, and liabilities accounts.

If the account is not showing up in both budget type, let's make sure to update your QuickBooks Desktop for Mac to the latest release. Here's an article for the instructions: Update QuickBooks Desktop for Mac. This helps improve the program's functionality and fix known issues. 

Then, open the program once the update is done and try to check the account in the budget page.

I'm adding this article for a reference: Create a budget or forecast in QuickBooks Desktop.

Otherwise, reach out to our Customer Care Team for further investigation by following these steps:

1. Go to this link: https://help.quickbooks.intuit.com/en_US/contact.
2. Select QuickBooks Mac Desktop.
3. From the Contact Us page, select any topics.
4. Under Here's how to connect with a QuickBooks expert section, click the Get Phone Number or Start a Message button.

Please feel free to leave a comment here if you have any additional questions or other concerns. Take care and stay safe.