Where do I setup how the driver's commission is computed?

Before printing driver's payroll, you need first to setup driver's payroll settings under the driver's profile (edit window).  

The settings may be different for each driver. If you pay a driver based on commission, then select the appropriate settings. Then when you settle a trip, LimoWiz will calculate the the driver's commission based on theses settings. See Settle Trip for more details.

Print, Preview Payroll and Verify Trip if They are Settled:
 
To access, see Reports menu or click the Payroll icon on top toolbar of LimoWiz.

You may view one driver at time or print a range of drivers’ payroll. Payroll dates are saved for the current period. LimoWiz does not compute the taxes. You can use any accounting package like QuickBooks Pro with payroll. All you have to do is take the Total Pay from the payroll report and enter in the accounting package.

You have several payroll report options to choose from, or you can save the report style in the driver’s profile as see in the first figure above.
 

To keep driver pay history on file, edit the driver and click on the Pay History button and add.

It is recommended that you print two payroll sheets, one for office use and one for the driver.

Each driver should have a folder of his own. Check stubs should be stapled as a proof of payment.
 

LimoWiz verifies if trips are settled, i.e. completed. If not settled, driver total for a particular trip will be zero. A trip is settled if Settled By field on trip settle window is NOT empty.

Note: If the trip is settled and you need to make changes, you must edit trip first and click the Recalculate button on Settled window.