Samsung
Change Clock Style on Lock Screen auf Samsung
The lock screen clock on Samsung phones is controlled separately from the display and wallpaper settings, which is why many users search the wrong menu first.
To change it, go to Tap on Settings ➔ Tap on Lock screen ➔ Tap on Clock style. From there you can pick between digital and analog layouts, decide whether to show seconds or the date, and adjust the color to match your wallpaper.
After selecting the look you want, confirm with Set the Clock style and change the Color ➔ Tap on Done to apply it to the lock screen immediately.
One detail trips up a lot of users: if Roaming Clock is turned on, the phone assumes you need a fixed clock format while traveling, and the style options become locked or limited. Turning off Roaming Clock in the same lock screen settings restores full control over the clock style and color.
This setting only affects the lock screen, not the always-on display or home screen widgets, so changes made here won't show up until the phone is locked.