Podcasting/Enclosures problem

I use my site mostly for podcasting.
Because I was doing music podcasts I had to make them streamable only so turned off the enclosures function that it prompted me about (this was months ago).

Now I want to turn this enclosure feature back on so I can create a podcast feed to submit to iTunes but I can’t find where to reset it?

I hope someone will be able to help.

Thanks