How to change description or publish date of an episode

After logged in, go to the main page, and click on the edit button of your desired podcast. Then, the edit screen will show the details of the podcast, then scroll down, you will find the list of episodes as shown. Then click on the edit button of the desired episode.

On the episode edit screen, you can edit description and publish date for the episode. Note that changing the publish date will change the order of the episode.