Changing multiple still durations in timeline

I think I am missing something real simple here.

Trying to change the duration of multiple stills in timeline. I select multiple stills in timeline, click control D, go to the time window and enter 2.00 hoping to change each still to 2 sec. Hit enter and nothing changes but the curser goes to the 2 sec mark on the time line.

Also, in preferences I have the duration set to 2 sec. for stills. When I drag individual clips into the timeline they are 2 sec long. When dragging multiple clips into the timeline they are 10 sec long. Can I drag multiple clips into the timeline and have them all be the still duration set in preferences?

Thank you! Andy