You have the ability to
Go to the jobs view page where you see the list of jobs. Then click on "open menu" on a job row
Below you will see the areas where can go and edit the job. It's circled. You will see that area when you click on the "open menu" button on the job row.
When you click on "edit time of event" a dialog popups that shows you the same time input area that the customer was shown at checkout. You can enter in a new time and it will be the new time of the job.
Below you will see the dialog with the daily style time inputs
If you edit a job that has a payment style of fixed rate you can adjust the inventory for the job but you can't change the payment in the edit section.The fixed rate is like a standard deposit. You can make payments and refund for a job the payment and refund areas