Display brightness keeps resetting
QWhen my iMac Pro starts up, the display’s brightness resets. As the display is calibrated for photography, this is annoying. How can I get it to stick?
AEnsure that you have the current release of High Sierra installed, as previous versions have had issues with display support. Then go to System Preferences’ Displays pane and check that automatic brightness adjustment is turned off in the General tab, and that Night Shift is turned off in its eponymous tab.
Go to the Accessibility pane too: its Display section contains controls for managing the display. All options there should be turned off and contrast set to Normal.
Remaining problems are down to the file that stores your preferences. In High Sierra, this should be com.apple.systempreferences. plist in /Users/[your account]/Library/ Preferences. The traditional remedy of editing or removing that is usually ineffective now, because macOS runs a background service to manage preferences.
Check those files have the correct permissions: test them using my free app PermissionScanner, from eclecticlight.co/ downloads. You can then hone in and correct any that aren’t writable.
Apple has also documented a process for repairing incorrect permissions for files stored in your Home folder, which is detailed at bit.ly/macperms. If all else fails, trash that preferences file, restart your Mac, and set up the brightness controls again.