Q: 10.1.1 - How do I alter the time on multiple photos all at once

Hello, would be so grateful for some help.

I am using version 10.1.1 of iMovie, on my MacBook Pro (10.11.1).

I am making a time-lapse, and imported hundreds of photos.

I see in other versions of iMovie that I can select them all (which I do know how to do) and then

do a group length change.... but in this version I am not seeing this option.

I would love some guidance - THANK YOU! (and if one can do group, image correction or filters??)

Amy