This video will show you the easiest way to authorize SmartThings newly added devices to other SmartApps. Typically you can do this in two ways go to the application of the SmartApp or go into SmartThings.

Once you have connected your SmartApp like SharpTools to SmartThings the easiest way to authorize new devices is to go into the SmartThings App and authorize which devices the SmartApp will be able to use. By using this method you will get every available option so you will be sure to authorize all devices by using the second authorization screen.