What is Accessibility shortcut? (For Android™ 8.0 (Oreo)™)

By pressing and holding the MUTING button on the remote control for three seconds, you can turn your desired accessibility function on or off.
The default assignment for the shortcut function is screen reading function such as Screen reader or TalkBack.                                                  
To change the assigned shortcut function, refer to the following steps.

1. Press the Home button on the remote control.
2. Select  Settings.
3. Select Accessibility in the System Preferences category.
4. Select Accessibility shortcut.
5. Select Shortcut service.
6. Select your preferred accessibility function such as Text magnification.