Hammerhead Karoo is able to connect with other third-party service providers & upload activities straight from the device. "Automatic" and "Manual" Activity Upload Modes are applicable only for Strava, Training Peaks, and Ride With GPS for now.
To learn how to connect third-party services, please see: Linking Third-Party Accounts
Here are the steps to change between Automatic and Manual upload modes:
Tap on "Settings" from the Home Screen
Scroll down and tap on "Connected Services"
You will have the option to toggle between "Automatic" and "Manual" Activity Upload modes.