The Purchase Details section is a placeholder. It represents what type of data will be printed there. When editing the Thank You Message, this section cannot be edited except to change the font name or size. The section can be removed, if desired.
If the purchase details section has been removed and you want to add it back, please enter a ticket to the support team for assistance.
The purchase details will list all the ticket levels, add-ons, and fees included in the transaction. Below that section is the Purchase Details totals, which are editable to include whichever items are applicable to your event. You can remove a line, such as Coupon Discount Amount, if that does not apply to the event.