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Strummer_S
User level: Level 1 (4 points)

Second Monitor Registering as Wrong Size

I am trying to use a second monitor with my iMac, and I cannot change the ratio of the displays. In the display settings the Mac is set to be bigger even though the Mac is 24 inches and the other display is a 27 in. LG Ultrafine. Its causing a "shelf" where the mouse gets stuck at the top and bottom where it thinks the mac extends beyond the screen of the LG. It has also caused the mouse to jump when moving between screens.

Posted on Oct 8, 2026 7:55 AM

3 replies

den.thed
User level: Level 10 (99,154 points)

Oct 8, 2026 8:28 AM in response to Strummer_S

That is normal for two different sized displays in Extended Desktop Mode.


Try this, go to Apple > Settings > Displays and click Arrange... move the Extended display down so that the top of the displays line up and live with the blockage at the bottom.


Grant Bennet-Alder
User level: Level 10 (148,617 points)

Oct 8, 2026 8:12 AM in response to Strummer_S

EXACTLY what model LG Ultrafine 27-in?

How is it connected to your Mac?


Grant Bennet-Alder
User level: Level 10 (148,617 points)

Oct 8, 2026 8:20 AM in response to Grant Bennet-Alder

if you are not 'Mirroring' the displays, then Extended Desktop will concatenate the displays along an edge of your choosing to produce a much larger "Extended Destop".


This is illustrated in this older screenshot of the Arrangement pane:





Originally posted at discussions.apple.com/thread/256372557