Help with 27" iMac as 2nd display
I have two 27" iMacs connected together with a mini-DP cable. I want to use one as a second display. I connected them together and pressed cmd-F2 on the 2nd display, but nothing happened. I tried cmd-F2 on the primary, also nothing happened. I have the following setup:
iMac 27" (Late 2013) High Sierra - I want this to be primary
iMac 27" (Late 2012) Catalina
iMac 27", macOS 10.13