Note: Only applicable for basic accounts. If you have a Premium subscription account, head over to the My Stuff, open your design to edit and download it.
Your purchased download cannot be changed by opening it through 'My Stuff'. Instead, the design needs to be updated, and then generated again as a high-resolution download.
To make the changes, go to 'Order History', and click 'Make a Correction', beside the download button. You'll be redirected to the editor and prompted to make changes. Once you've finalized the changes, click 'Save and Recreate Order'.
The high-resolution download will generate and will be ready in 5-10 minutes. You'll receive the new download from the Download page.
Keep in mind these changes can be made 3 times. On exceeding this, you will be prompted to purchase the design again.