Once this is enabled, a button will appear on the Shopping Cart page beside the Update Cart or Empty Cart button:
User-added image

To configure the Continue Shopping button in web forms: 
  1. Click Web > Click Web Payment Settings
  2. Mark the Display Continue Shopping button checkbox
  3. Choose what page you want to direct users to: 
    1. If you want to direct users to the previous Altru web form they were on prior to checkout: Choose Previous Altru Web Form
    2. If you want to direct users to a specific URL on your website: Choose Specific URL and enter the URL of your choice
  4. Click Save