Wrong language displayed by SDDM on login Kubuntu 18.04

Question

After hearing good things about KDE Plasma, I decided to give Kubuntu 18.04 a spin. I was impressed until it came to the long in screen. The biggest issue I had was the language of the date and time displayed on the “Login” and "Lock" screens.

I am an American Expat who lives in Thailand. I have no problem with changing the regional settings from the installed defaults to something I am familiar with. No matter what regional or language setting I changed on Kubuntu, it would always display the date and time in Thai format on the login/ lock screen. The keyboard IS set to American QWERTY and I can login just fine. It is just the Date/ Time being displayed in the wrong language.

Every possible setting in the "System Settings-Regional Settings-Language" and "System Settings-Regional Settings-Formats" is set to "American English" I have also ran sudo dpkg-reconfigure locales in the terminal and made sure the en-US UTF8 was chosen. All to no avail.

Here is a screenshot of what it is doing. I have shown it side by side with the Manjaro version to show exactly what I am talking about.

I am at a total lose as to what to do. Any ideas? Thank you all for your time.

Answer 1

SDDM login screen

KDE Forums: https://forum.kde.org/viewtopic.php?t=137502#p375121 and What locale settings sddm respects?: https://www.bountysource.com/issues/37982685-what-locale-settings-sddm-respects

The SDDM is following the system locales defined in /etc/default/locale:

LANG="en_US.UTF-8"
LC_NUMERIC="fi_FI.UTF-8"
LC_TIME="fi_FI.UTF-8"
LC_MONETARY="fi_FI.UTF-8"
LC_PAPER="fi_FI.UTF-8"
LC_NAME="fi_FI.UTF-8"
LC_ADDRESS="fi_FI.UTF-8"
LC_TELEPHONE="fi_FI.UTF-8"
LC_MEASUREMENT="fi_FI.UTF-8"
LC_IDENTIFICATION="fi_FI.UTF-8"

LC_TIME is "fi_FI.UTF-8", so the SDDM Breeze greeter will show:

Changing to US time: LC_TIME="en_US.UTF-8"

LANG="en_US.UTF-8"
LC_NUMERIC="fi_FI.UTF-8"
LC_TIME="en_US.UTF-8"
LC_MONETARY="fi_FI.UTF-8"
LC_PAPER="fi_FI.UTF-8"
LC_NAME="fi_FI.UTF-8"
LC_ADDRESS="fi_FI.UTF-8"
LC_TELEPHONE="fi_FI.UTF-8"
LC_MEASUREMENT="fi_FI.UTF-8"
LC_IDENTIFICATION="fi_FI.UTF-8"

After reboot:

To edit the/etc/default/locale you can simply edit it with a text editor or execute the 'update-locale' command (see 'man update-locale' or https://manpages.ubuntu.com/manpages/bionic/man8/update-locale.8.html).

Plasma Lock Screen

Plasma lock screen is part of the Plasma Look and Feel theme, which is not the same as the SDDM greeter theme.

Plasma lock screen is configured in the KDE System Settings

Setting the Time format:

... and the Plasma lock screen shows:

Alternative SDDM greeters and Plasma lock screens

The KDE Store: https://store.kde.org has many alternative SDDM themes: https://store.kde.org/browse/cat/101/ord/latest/ and Plasma Look and Feel themes: https://store.kde.org/browse/cat/121/ord/latest/

It is possible to add the time format settings to the SDDM greeter configuration files. An example: SDDM Theme Breeze Slider 2 - https://store.kde.org/p/1222217/

...and from the Plasma 5.12 onwards it is possible to add clock configuration options to the lock screen settings. An example: Breeze Custom Lock Screen - https://store.kde.org/p/1216681/ .