Changing Still Image Clip Durantion

I know how to do this but I am having trouble because FCP just won't change the still image duration for the clips. I have to manually select each image and change the duration in the top left of the browser. If I select all the images (which are all the same duration, I just need to shorten it) or even 5-10 at a time, and right click, I get the duration option, change the time but I just get the "can't do it" click and nothing changes. I have tried the selections linked and unlinked. Nothing seems to help. It will take me forever to manually change one at a time, anything I am missing?