sound option: on/off always return to default

[shinichi7]

i've created a qml file soundOption.qml

function toggle() {
        if (soundOption.state == "on")
            soundOption.state = "off"
        else
            soundOption.state = "on"
    }

function toggle() {
        if (soundOption.state == "on")
            soundOption.state = "off"
        else
            soundOption.state = "on"
    }

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when accessing to other qml, it is always in default setup.

default is "on", then i switched it to "off"
when i am on other qml and i want it to switch back "on", it was already "on"
i can only switch it on and off when i am on the same qml file...

in other qml file:

soundOption {
....
onClicked: soundOption.toggle()
}

soundOption {
....
onClicked: soundOption.toggle()
}

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pls help