Reason: To change the temperature unit, I need to access the settings or options menu, which is likely accessible through the 'list' tab at the bottom right. Action: Tap on element with ID 20.
Reason: The 'more' icon at the top-right corner likely provides additional options or settings, including the ability to change the temperature unit to Celsius. Action: Tap on element with ID 2.
Reason: The 'Celsius' option is visible in the dropdown menu. Tapping on it will change the temperature unit from Fahrenheit to Celsius, achieving the goal. Action: Tap on element with ID 7.
Reason: The temperature unit has been successfully changed to Celsius, and the goal has been achieved. No further actions are needed. Action: Terminate the session.