Your previously exported videos will be under the Exports section on the 🔳Home page.
Click on the ≡ (menu button), then 🔳Home, and all your previously exported videos will be under the Exports section.
From here, you can click on the video you would like to access.
On the next page, click the option on the right where it will show you your exported video's prompt title, as highlighted below.
Once clicked, you will be redirected to the generation page, where you can edit your video!