You set your Mac or Macbook which disk to start up from when more than one startup disk is connected. This works for USB drives including the NinjaStik
For 2018 to 2020 Macs with the Secure Boot T2 Chip, see the 2020 Macbook Pro Boot from USB instructions.
Choose Apple menu System Preferences, or click the System Preferences icon in the Dock. Then click the type of preference you want to set. To learn more, see Customize your Mac with System Preferences in the macOS User Guide. In System Preferences, click Software Update to see if your Mac is running the latest version of macOS. How to Access System Preferences on a Mac. Use Launchpad – You can open the Mac’s Launchpad by clicking on its icon in the dock or via a hand gesture by pinching closed with your thumb and three fingers on your trackpad. Once Launchpad is open, simply click on the System Preferences icon to open it. Use the Dock – You can choose to keep.
A “startup disk” is a volume or partition of a drive that contains a bootable operating system.
A brief guide to what can be found in System Preferences on the Macbook.
You can set your Mac to automatically use a specific startup volume, or you can temporarily override this choice at startup.
The next time you start up or restart your computer, your Mac starts up using the operating system on the selected volume.
Startup Manager allows you to pick a volume to start from while the computer is starting up.
Use these steps to choose a startup disk with Startup Manager:
If you have an optical drive connected to your computer, you can insert an installation disc to see it in Startup Manager. You can also attach FireWire or USB external hard drives that contain an operating system to add to the list of startup volumes.
Startup Manager automatically adds bootable volumes as you connect them.
If you have started up your Mac in Windows using Boot Camp, you can use the Boot Camp system tray to switch your startup disk default back to OS X.
You can also start your Mac from OS X Recovery or Internet Recovery if your Mac was manufactured after 2011.
To start your Mac from the Recovery System, use these steps:
If you don’t see the volume you want to start your computer from, check the following:
For 2018 / 2019 Macbook Pro with the Secure Boot T2 Chip, see the 2018 Macbook Pro Boot from USB instructions.