Is there a way to return all values of all widgets on a screen to their default values (ex. TextInputs text: '') or do I have to write a function to go through each one, one by one, to clear them?
What you can do is clear all widgets on a screen using .clear_widgets() function. I don't think there's any way to reset all values. Another way to change the values is like if you have a textfield then you can do textfield.text = '' but you have to go through each widget to reset it
Kivy: Reset/Default values to all widgets on a screen?