secondary monitor
Help! I have a 2013 iMac running on Catalina. I have tried to set up a second monitor, with no luck. Tried a new GTEK external monitor utilizing all sorts of different ports/connections. And, tried to use my old 2010 MacBook Pro. Nothing. But, the GTEK monitor worked fine with my husband's 2017 iMac. I don't get it. Ideas? Thanks so much!
iMac Pro