buildstring_screenmanager.kv

<TaskScreen>:
    GridLayout:
        cols: 2



<SettingsScreen>:
    BoxLayout:
        Button:
            text: 'My settings button'
        Button:
            text: 'Back to menu'
            on_press: root.manager.current = 'menu'
<TaskDetailsScreen>:
    BoxLayout:
        orientation: "vertical"
        GridLayout:
            cols: 1
            Label:
                text:"Test Label"
            TextInput:
            Label:
                text:"Test Label"
            TextInput:
            Label:
                text:"Test Label"
            TextInput:
            Label:
                text:"Test Label"
            CheckBox:
            Label:
                text:"Test Label"
            TextInput:

        Button:
            text: 'Back to menu'
            on_press: root.manager.current = 'menu'