To access a customer's job history from your dashboard, click 'Customers' in the upper left of your screen.
Click on the customer whose job history you would like to see.
Once in the profile you will see a Profile tab, Jobs and estimates tab, and Billing history tab. You will want to click on the Jobs and Estimates tab to see the history.
You are also able to customize what columns are showing and add date filters to easily find jobs if the customer has a lot of history.