I have Thunderbolt USBC connecting my iMac and MacBook laptop. I have restarted. I have Displays open, but the Detect Displays button will not appear, even when I press Option
iMac Line (2012 and Later)
The chances are VERY good you are wasting your time. Unless you have a very small subset of Macs it won't work, please refer to Target Display Mode (Target Display Mode) to see what will work. To be perfect honest, you would be much wiser to simply buy an external display for you MB and move forward.
You can use most any after market external display with the iMac and/or the MacBook.
for the iMac see > https://support.apple.com/guide/imac/connect-a-display-apd8cdd74f57/mac
for other Mac's see > https://support.apple.com/guide/mac-help/use-external-displays-mchl7c7ebe08/mac
What year model are your Mac's?
Only certain older Mac models supported Target Display Mode.
carefully study > https://support.apple.com/en-us/HT204592
Thanks everyone, but I have learned that this is completely not an option with my brand new iMac and MacBook. I am highly dissappointed as this was something I was looking forward to and just assumed was something that was doable since I know so many people that use multiple monitors. (I guess they are all PCs users.) Really am very upset that my very expensive new computer does not allow for dual monitors. Regretting my purchase.
If you were looking forward to it then you certainly should have done your due diligence to discover what can and cannot be done. Apple never misled you, you simply did not do your research. You can use any external display to work, that is simple to setup and MUCH more reliable than Target Display Mode ever was.
i connected my imac with my mac book but the detect displays button wont appear
