Begin by clicking on the blue "View all activities" link at the bottom left of the widget.

Click on "More actions" and then "Dismiss until."

Choose between "specific date, next submission," or "forever." Restore dismissed items by going to back to the "View all submissions" screen. Next click on the elipses at the top right of the page and then click "Dismissed activities."

Choose the items you'd like to restore from the list.