How do I assign content to multiple devices?

How do I assign content to multiple devices?

1. Go to content> search campaigns and select your campaign
2. Click on 'View assignments' (top left hand corner)
3. Click on 'Toggle filter' (top left hand corner)
4. Select 'include subfolders' and filter by device
5. Select multiple devices by clicking and holding SHIFT and deselect using CTRL 
6. You can then assign content using the plus (+) icon