Once you have added a source to the 'Discover' feed, you can also change its details, including the name and the source type, by clicking on the 'Manage Sources' button found in the 'Discover' tab.

Click on the gear button associated with the account you want to edit and you’ll be able to change the information regarding the import source you have previously added.

If you are editing a content source added by one of your colleagues, the ownership of that content source will automatically be transferred to you. So, once you have saved the changes, the source will be tied to your account, and you will need to have a suitable social account connected in order to edit the source.