Andrew, on the top of that "global price update" page are options to search for "image name", "image keywords", "gallery name", or "artist name". And just below that is the option to "show all images". If you want to just change prices on all your images, you would:
- select that option to "show all images".
- When all the images show up, select the check box next to the column heading labeled "image column".
- Once you select the check box, all the images on that page should be automatically selected, and you will see an additional option labeled "select all [xyz] images on all [abc] pages (just below the column heading), select that too.
- When ready, pick the button labeled "edit checked images simultaneously" and you should be able to change your prices on all your images at once.