Can't get any of my Macs to run a second monitor
Someone please help!
I have an Early 2016 MacBook, a mid 2010 MacBook Pro, and late 2012 iMac. I have purchased every adapter and cord reasonably expected to work. I have a Thunderbolt Cable. I have a Thunderbolt 3 to Thunderbolt 2 adapter. I have a Thunderbolt to USB-A cord. I have a USB-C adapter that can connect to HDMI, USB-A, and USB-C. I watched tutorials, tried to enter target display mode on each device, plugged the adapters into all the right ports on each respective device and I still can't run two screens between any of the devices.
Is this truly an impossible task or am I missing a key step?
iMac (21.5-inch, Late 2012), OS X Yosemite (10.10.5)