Can I manually adjust Federal, state, and FICA withholding amounts for a salary employee that is being processed automatically on a biweekly payroll run? How?

Yes, you can, userpebookkeeper.

QuickBooks automatically calculates federal withholdings depending on the information entered on the employee's W-4. If you want to adjust the withholding amounts, you'll need to go through each paycheck. 

Here's how:

1. Go to Payroll, then click the Employees tab.
2. Choose the employee's name and select the Paycheck List link.
3. Put a checkmark in the box from the selected employee. Then, click the Edit button.
4. You'll be routed to the Edit Paycheck page. 
5. Click the Employee Taxes drop-down arrow to expand the page.
6. Make any adjustments.
7. Once done, click on OK.

If you're having issues following the steps, I'd recommend contacting our QuickBooks Support Team. They can further check on your account and help you adjust the withholdings.

Additionally, I've added an article that'll help you view helpful information about your business and employees. This ensures your payroll details are correct: Run Reports.

Please let me know if you need clarification about this or if there's anything else I can do for you. I'll be waiting for your response,