iMovie Green Screen malfunction
I'm working with iMovie on my iMac. I have a background image on the lower timeline and an image with green background on the upper one. I select the upper greenscreen clip which highlights yellow. I go to the dropdown menu which is defaulting on Cutaway and select Green/Bluescreen. It defaults back to cutaway. No matter what I do, it will not let me select Green/Blue Screen. I rang Apple who suggested I create a new login - no dice. Can anyone help?
iMac 21.5″, macOS 10.15