The Parameter RAM (PRAM) stores settings related to your computer's devices and settings, such as volume, display resolution, and startup disk. To reset your PRAM, follow the steps below:
- Turn off the system.
- Turn the system back on.
- Before the gray screen appears, press and hold Command, Option, P, and R.
- As you hold down the keys, the system will restart. Wait until you hear the startup chime for the second time, then release the keys.
Note: Resetting your system's PRAM may set preferences to default settings. You can use System Preferences to readjust your settings according to your preferences.