Among quick fixes for many issues on a Mac are PRAM and SMC resets.
PRAM stands for parameter random access memory, which can contain settings such as speaker volume, screen resolution, startup disk selection, and recent kernel panic information. Performing a PRAM reset can fix a number of issues, such as wifi connectivity, drives not showing up or screens not adjusting properly. To do a PRAM reset, all that has to be done is turning the Mac device on and holding Command + Option + P + R until the machine chimes a second time. This process should be done for a longer amount of time on a Late 2016 MacBook Pro because it doesn’t have a startup chime. However, PRAM resets are actually a thing of the past. Today the majority of Macs in use; ones manufactured after 2008, actually primarily use NVRAM to store many of these settings. A PRAM reset and a NVRAM reset are mostly the same, it resets less volatile ram to default factory settings, fixing a number of potential issues. NVRAM stands for non-volatile random access memory and is reset in the same manner as PRAM is.
SMC stands for system management controller, this is only on Intel-based Macs. SMC resets reset this controller which is a part of the machine that deals with hardware and power management. This system management controller reset can fix problems dealing with the fans, lights, power and system performance.. There are a variety of ways to reset the SMC depending on the kind of Mac you’re working with. A desktop mac, such as a Mac Pro, Mac Mini, or iMac requires disconnecting the power cord from the machine, waiting 15 seconds, plugging it back in, waiting another 15 seconds and then turning the Mac back on. With a Mac laptop with a non-removable battery, shut the Mac down connect the Mac to its power adapter. Hold shift, option and control on the left side, then press the power button, release all keys and then turn the Mac on normally. For Mac laptops manufactured 2008 or before with removable batteries, turn the machine off, disconnect the power cable, remove the battery. Press the power button and hold for 5 seconds. Put the battery back in, reconnect its power cable, and turn the Mac back on.