I have a second display (Dell) connected to my iMac. How do I toggle the cursor between different applications on the different screens. My cursor cannot be dragged from one screen to the other--it stops at the border.
iMac 21.5″ 4K, macOS 10.15
Your mac probably thinks the Dell monitor is located on a different side. To test this try dragging the cursor off all four edges: one edge should lead to the second display.
To fix a location/alignment issue go to:
-> About This Mac -> Displays -> Display Preferences... -> Arrangement
You should see two blue rectangles representing the iMac and external monitor. By default the one with the white bar on top is your iMac. Click and drag the the other rectangle until it is on your right/left/top depending on if the dell monitor is right/left/above the iMac.
Your mac probably thinks the Dell monitor is located on a different side. To test this try dragging the cursor off all four edges: one edge should lead to the second display.
To fix a location/alignment issue go to:
-> About This Mac -> Displays -> Display Preferences... -> Arrangement
You should see two blue rectangles representing the iMac and external monitor. By default the one with the white bar on top is your iMac. Click and drag the the other rectangle until it is on your right/left/top depending on if the dell monitor is right/left/above the iMac.
it could be the arrangement which is not as you think
or maybe you put it into mirror mode rather than extending mode
try reading
Use external monitors with your Mac - Apple Support
I have a second display (Dell) connected to my iMac. How do I toggle the cursor between different applications on the two displays.
