Whenever you need to adjust something about your podcast (e.g. the Title, artwork, Author, etc.) you should go to the Edit Podcast page.
Start in the Podcasts Library and click on your podcast.
From this page click on "Edit Podcast" up in the top right:
This is the page where you can adjust many of the settings for your podcast including:
Podcast Title, Subtitle, and Summary
and many more!
Note: the "Tags" field is only used by Ad Ops users and does not refer to iTunes tags. Anything entered here will not be included in your RSS feed.