Oppo
Set Time Manually auf Oppo
On Oppo phones running Coloros, the clock syncs with the mobile network by default. This keeps the time accurate while roaming or switching towers, but it also removes the option to enter a custom time. If you need a different time for testing, travel, or a broken network signal, you first have to disable this sync.
Open Settings ➔ Additional settings ➔ Date & time. Inside this menu, turn off Set automatically. Once the toggle is off, a new field labeled Time appears. Tap it and set the time you want.
Keep in mind that disabling network time also affects how your phone reacts to time zone changes. If you travel afterward, the clock will not adjust on its own until you turn Set automatically back on. This is a common source of confusion when alarms or calendar events suddenly appear off by an hour.
If your issue is only a wrong time zone rather than the clock itself, check the time zone setting in the same menu before disabling automatic sync entirely. Switching off network time is only needed when you want full manual control over the displayed time.