select track(s)
right click
select "get info" *
select "options"
look at "media kind" & see what it says.
select drop down menu & change to "podcast"
you can do the same if you've imported audiobooks, or want to tag something as an audiobook
* if you select one track you get a slightly different menu when you select "get info", but the "option" tab is still there.
HTH