Stop things popping up when your pointer touches a screen corner

Why it happens

A Hot Corner runs an action the moment your pointer reaches that corner of the screen. Common ones are Mission Control, which zooms everything out to show all your windows, Quick Note, Desktop, Notification Center and putting the screen to sleep. It's easy to fling the pointer into a corner without meaning to, especially on a big screen or while presenting.

How to fix it

1. Choose Apple menu, then System Settings, and click Desktop & Dock in the sidebar.

2. Scroll down to the Mission Control section near the bottom and click the Hot Corners… button.

   Desktop & Dock›Mission Control›Hot Corners…

3. You'll see a pop-up menu at each corner. Click the one for the corner that keeps triggering and choose the dash (-) to turn it off.

4. Want to keep the action for when you need it? Hold down Command (or Option, Shift or Control) while you choose the action in that pop-up. The menu shows the key next to the action, and the corner then only works while you hold that key.

5. Click Done, then move the pointer into the corner to check nothing happens on its own.

Still not fixed?

1. Notes keep opening from the bottom-right corner? That's Quick Note. Set that corner to the dash too. You can still start a note when you want one with Fn-Q.

2. If everything zooms out when you swipe on the trackpad rather than at a corner, that's the Mission Control gesture. Change or turn it off in Trackpad settings under More Gestures.

   Trackpad›More Gestures›Mission Control

3. If windows zoom out when you drag one to the top of the screen, turn off Drag windows to top of screen to enter Mission Control in Desktop & Dock.

   Desktop & Dock›Mission Control›Drag windows to top of screen to enter Mission Control

4. If things still open by themselves with every corner set to the dash and no gestures in use, try another mouse or trackpad. A faulty one can send stray clicks or swipes, which a repair shop can check. If another works no better, contact Apple Support.