Help: SigFeed Settings
You can get to a SigFeed's settings page by selecting "Modify Settings" from that SigFeed's Action menu on the Your SigFeeds page.
On the Settings page, you can specify the blog and feed address for that SigFeed. These form controls work pretty much the same as the ones you used to create your SigFeed.
You can also switch your SigFeeds between Scheduled Updates and Ping Updates.
And that's about it.