Use VoiceOver activities on Mac
Use VoiceOver activities to create groups of preferences for specific uses. For example, create an activity to use a certain voice and faster speaking rate when you shop online, then create a second activity to use a different voice and slower speaking rate when you read online articles.
Note: VO represents the VoiceOver modifier.
Set up activities
Open VoiceOver Utility (press VO-F8 when VoiceOver is on), click the Activities category, then click the Add button
to create an activity.Type a name for the activity, such as “Online Shopping.”
To rename an activity, select the activity in the table, press Enter, then type a new name.
For each setting you want to customise for this activity, select the checkbox, then click Set.
To show all the settings you can customise, click the disclosure triangle to the far right of Hot Spots.
To have VoiceOver automatically use the activity for certain apps or websites, click the Apps & Websites button.
To specify apps, choose one from the pop-up menu, or choose Other App to browse for and select apps.
To specify websites, click Websites, click the Add button
, then enter the URL of the website, such as www.apple.com. To remove a website, select it in the list, then click the Remove button 
.An app or website can be associated with only one activity. If you select an app or website that’s associated with another activity, you’re asked if you want to change it.
To duplicate an activity that you set up, select it in the list, click the Action button 
, then choose Duplicate Activity. Any apps or websites specified for the original activity are not included in the duplicate. To rename the duplicate, click its name in the list, then type a new name.
Use an activity
If you switch to or open an app or website with which you associated an activity, VoiceOver identifies the activity (if verbosity is set to Medium or High).
Manually choose an activity in the Activity Chooser: Press VO-X to display the Activity Chooser, use the Down Arrow and Up Arrow keys to navigate the list until you find the one you want to use, then press Return.
Use the previous activity: Press VO-X-X.
Exit the Activity Chooser without making a selection: Press the Escape key or Fn-Tab.