Why is my custom resolution missing at the FileVault unlock screen?

BetterDisplay cannot set the resolution of the FileVault startup unlock screen. Its display adjustments run in your macOS user session, so a setup that works after you sign in may still be unavailable during startup.

FileVault requires authentication during the boot process. That startup unlock screen is different from the screen you see when locking an already running desktop. Enabling BetterDisplay to open at login cannot make it apply settings before this unlock step.

Custom scaling and software EDID overrides configured in macOS do not rewrite the monitor's own advertised capabilities. Do not assume that a working overridden mode will also be available at startup, in boot options or in Recovery. Some system configuration changes persist without the app running, but that does not turn them into startup-firmware settings.

If the startup picture is unusable, use a display and connection that can show the Mac's normal startup output—for example, the built-in display on a MacBook or another working monitor on a desktop Mac. This lets you sign in before BetterDisplay applies your usual setup. Changing the preferred mode inside the app cannot guarantee that the startup unlock screen adopts it.

If the problem happens after sleep rather than after a restart, see Generic Display after wake. That is a different stage of display detection.