To have this option you need to have TTT-Social plugin installed.
Also you can go directly to the customizer social feed settings from Dashboard Theme Settings Overview.
Inside the Customizer
There are two options:
- Feeds position. If you write 0 the feeds widget will be after all posts. From 1 and above is the number of post to show before the feeds widgets.
- Select if you want to show the social feeds in masonry streamline.
All the feeds sources have Feed Limit where you can define how many entries of each one you want to show in the widget.