Medved Trader can connect to multiple data sources to gather the data to show you. Often, one data source can supply multiple kinds of data (for example, a source can give you Level I and Level II quotes, intraday and historical backfills and news). For MT to use the data source, it has to be set up first in this settings section.
Configure Accounts - here you would enter the login information and other settings for various data sources, such as brokerages, free and for-fee data sources.
News - here you would set which news sources are active and on which portfolios's symbols the news is being collected.
Option_Chains - in order to enter Option symbols in Medved Trader, you have to have the option chain data source to provide all available options for a particular security. Here is where you select which option chain data source will be used.