When you reach the final question, you will have the opportunity to go back and review your answers one-by-one before you submit. You can use the PREV/NEXT button or the menu on the left to navigate.
Please note that if the timer runs out while you are reviewing your answers, the exam will not automatically submit for you, and you will fail. You need to submit your answers. You can always get back to the submission screen by clicking "Submit" in the upper right corner.