Follow the below steps from the VaxCare app home screen on the device.
Changing language back to English:
Swipe up from bottom of screen
Tap the circle in the bottom of screen
From the device home screen, tap settings (looks like a grey gear)
Scroll to the bottom and select system (last option on screen)
Tap Languages & Input (top option on screen)
Tap Languages (top option on screen)
Click the plus button to add a language, select English (United States)
Use the hamburger menu to drag English above any other languages
Tap the three dots in the top right of the screen & tap remove
Select the language you would like to remove
Tap the trash can in the top right & select OK to confirm