Plug in the other Tails USB stick that you want to install from.

Plug in your Tails USB stick.

[[!img install/inc/screenshots/mac_option_key.png link="no" alt="'Option' or 'alt' key in the bottom left of Mac keyboard"]]

Choose the USB stick and press <b>Enter</b>. The USB stick appears as an external hard disk and might be labeled <b>EFI Boot</b> or <b>Windows</b> like in the following screenshot:

If the USB stick does not appear in the list of startup disks:

[[!inline pages="install/inc/steps/basic_troubleshooting.inline" raw="yes" sort="age"]]

If your Mac displays the following error:

Security settings do not allow this Mac to use an external startup disk.

Then you have to change the settings of the <em>Startup Security Utility</em> of your Mac to authorize starting from Tails.

Read more on Apple Support about:

<a href="https://support.apple.com/en-us/HT208198">Startup Security Utility</a>

<a href="https://support.apple.com/en-us/HT204455">How to set a firmware password on your Mac</a>