Trying to set up extended display option with new MacBook Air. I do not see Arrangements tab under Displays

What do you see on your external Display at this time? Is it in Mirror mode? Do you see your desktop on it at least?

While connected to the Display, open System Preferences and then Displays. Hold down the OPTION key and that should reveal the DETECT DISPLAYS button. Click on it with your mouse and see if detects the external display and shows the Arrangements tab.

Also uncheck the Mirroring option if it is checked.

Axel F.

Are you trying to use Target Display Mode? It is not going to work between the two computers that have chosen.

Note: Target Display Mode isn’t supported on iMac models with Retina display. Only iMac (27-inch, Late 2009), iMac (27-inch, Mid 2010), and iMac (Mid 2011 to Mid 2014) support Target Display Mode.

Axel F.

I'm having the same issue. I can't see an arrangements tab in displays.

I can connect my external display to my Macbook air and it will project to the screen, but not to my macbook screen.

Mirroring is off. Detect screens doesn't do anything.

Not sure why this continues to happen?

I'm having the same issue! Trying to use my Mac (2015) as an extended display for my MacBook Pro (2017). Using the converter for Thunderbolt 3 and corresponding cable, but no luck. When I'm on the Display preferences for MacBook there's no tab for "arrangement." Was able to click "detect displays" but nothing happened. Could it be a compatibility issue?

I'm having the same issue. And when I clicked on the Option Key, the "Detect Displays" button does appear, but I'm not able to click on it. Do you have any further guidance if I'm stuck at that point? Thanks.