Reinstall OS X: Select Reinstall OS X and click on the Install button. The Erase button and wait until the process has completed. The Security button and set the Zero Data option to one-pass. Set the format type to Mac OS Extended (Journaled.) Optionally, click on Click on the Erase tab in the DU main window.ģ. After DU loads select your startup volume (usually Macintosh HD) from the Select Disk Utility from the main menu and click on the Continue button.Ģ. Restart the computer and after the chime press and hold down the COMMAND and R keys until the menu screen appears.ġ. However, I don't quite get what you are doing to reinstall Yosemite because you don't need to use the App Store directly.īe sure you backup your files to an external drive or second internal drive because the following procedure will remove everything from the hard drive. There is no cost for Yosemite, however, you must have a valid and active account which means a current credit or debit card.