Change time on lock screen to 24h format

Navigate to the following directory: 

cd /usr/share/plasma/look-and-feel/org.kde.breeze.desktop/contents/components

Then edit Clock.qml: 

sudo nano Clock.qml

Find the following line: text: Qt.formatTime(timeSource.data[“Local”][“DateTime”])

And edit this line to the following: 

text: Qt.formatTime(timeSource.data["Local"]["DateTime"], "hh:mm:ss")

Remove :ss to just display hour and minute. Finally reboot.

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