This option has the following selections.
Select single or multiple categories from the list to where comments will be applied. Comments option will be available for subcategories if parent category is selected.
Facebook Application ID
You will want to add this if the Facebook comments is chosen.
Width of the comments plugin in pixel, eg. 500. Note: Facebook doesn't provide a Facebook Comment code for responsive (fluid grid) websites. It uses only static width for it's comments box.
Comments Per Page
Set the number of comments to be displayed per page.
Show comments count on blog view or front page.