NVRAM or PRAM

A small amount of your computer’s memory, called non-volatile random-access memory (NVRAM) or parameter random-access memory (PRAM), depending on your type of Mac. NVRAM and PRAM store certain settings in a location that macOS can access quickly. The settings stored depend on your type of Mac and the types of devices connected to it, and can include the designated startup disk, display resolution, or speaker volume.