Update your Mac (OS and hardware) Typically, Macs take care of themselves. Having the latest software from Apple makes speeding up your Mac simple. To check your version of the operating system, click the Apple icon in the top left corner of your screen and then About This Mac. Here’s how to do it. First, shut down your Mac, press the start key (or button). Then quickly hold these combination keys: Command + Option + P + R, right after you hear the startup sound. Then release the keys when you hear the sound for the second time.
If you made a Time Machine backup of your Mac, Migration Assistant can use that backup to restore your personal files, including apps and everything in your user account.
If you prefer to restore just a few files or earlier versions of those files, learn how to use Time Machine to restore specific files.
If you need help, please contact Apple Support.