Re: Is there a setting that will allow me to exclude mobile app placements of my display ads?
This is how you do it.
Making sure your ad doesn't show on mobile apps
If you decide that a mobile app isn't where you want your ad to show, you can use the Site and Category Exclusion Tool to make sure your ads don't show on them. Simply exclude the placement called "adsenseformobileapps.com" from your list of placements.
Find more information here.
Hope this helps,