I'd like to resize the selected partition, but I can't drag it down. Any way to resize it?
Sorry , I can not see your screenshot clearly . by the way what kind of partition tool you are using now ?
This is Mac Disk Utility - but the screenshot is sooooo small it's hard to tell what anything is. All I can tell is the external drive already has loads of partitions on it.
I'm betting you need to delete the partition after the one you're trying to grow and then expand - but you'll lose all the data on the one you delete of course.