How to change your video trailer in YouTube One when the selector tool (small pencil) is not working. It's not a cure, only a "work-around" but one that you probably won't be needing too often. I've also included a little tip showing how to "Save" your video trailer change when you are unable to see the Save tab.
TIP: For those having a problem changing their large channel art graphic there are two problems. A) they're not accepting .PNG files, and B) the file size limit is somewhere around 1 MB.