To use the Manage Images Bar you first need to select the images you would like to update. You can do this two different ways depending on your personal preference.
Click the checkmark icon on each image you want to select. Be careful to not click outside the checkmark, otherwise you will open that image. A selected image will have a dark border and checkmark in the middle.
If you hold down the SHIFT key on your keyboard you can click anywhere on the image thumbnail to select it. Using this method speeds up the process of selecting large groups of images.
How do you Select All?
There is a third option to select all the images on the page. To do this simply click Select All from the Manage Image Bar on the right of the screen. You can also clear the selection by clicking the button again.