To set up the accessibility shortcut (activated by a triple click on the Home or side button) do as follows:
Go to Settings/Accessibility';
Scroll down to the final page and tap on Accessibility Shortcut.
Ensure that VoiceOver is selected and that no other items are selected.
Once this setting is made, VoiceOver can be turned on and off with a rapid triple click of the home button or on the side button for devices without a home button. Some users find this action difficult, so please try this with a person you’re helping and if they find it difficult, leave VoiceOver turned on for them and advise them that VoiceOver can also be turned on and off using Siri.
Several items may be ticked in the accessibility shortcut but be aware that if more than one item is ticked, the user will be presented with a choice after the triple click. This is OK when VoiceOver is on since it will be possible to swipe to find the desired item to turn on or off. However, if VoiceOver is off, sight will be necessary in order to turn it back on by locating VoiceOver in the menu visually and tapping.
The default speech rate may not be right for everyone and it may be changed in the Settings/Accessibility/VoiceOver menu. Speech rate can also be changed using the rotor.
Note that the speech rate can be changed while VoiceOver is off but this isn't recommended. If you learn a little VoiceOver then it’s better to change it with VoiceOver on to hear the effect immediately.