Hello Naomi,
If by format you mean .pdf or .dox, you may change this by selecting from your desired format from the format box at the right section of that box.
After doing some research, I have found this document. Here, I found this blurb: Using this functionality consumes ArcGIS service credits. To help you estimate how many credits you'll use, see Understand credits.
It seems that running these particular reports will gather information on the areas you have selected, thereby consuming credits. I would suggest that you let your user's know that this function may consume credits, and I would encourage you to send out this document to your workforce as well. Hope that helps!
Keep on keeping on!