The "General" section of the preferences has several options that control the behavior of the application.
Check for updates controls how often On The Job will check with Stunt Software's computers to see if a newer version is available.
Number of minutes before idle warning controls the length of time that On The Job will allow the computer to be idle (no mouse or keyboard activity) with a job running without offering to subtract that time when you return to your computer.
Show badge or time. These settings allow you to cause an indicator to appear in the dock when a timer is running.
Show confirmation before deleting tasks. With this setting checked, a warning dialog will appear to confirm that you want to delete a task.
Default Hourly Rate. When you create a new job, it will use this value as it's hourly rate. Jobs already created will not be effected when this setting is changed, and individual jobs can be set to any hourly rate you like.
Date Format controls how the date will appear in invoices as well as in the task list.