You can change active sources under 'Project Settings' in the Sources tab

This way, you can mark or unmark which sources you want to receive mentions from, e.g., if you just need data from the Web, then you can untick the rest and have results only from this category. 

Hopefully, that clears that up for you! But if you have any other questions, feel free to contact our live Customer Success team, we will be more than happy to help you set your project up.