Oppo
Change Time Zone Manually auf Oppo
On Coloros, the time zone is normally detected through your mobile network. Switching SIM cards, roaming abroad, or connecting to a weak signal can make the phone pick the wrong region automatically.
The result shows up in small but annoying ways: call logs with the wrong timestamp, alarms firing at the incorrect hour, or calendar entries shifting after a network change. As long as automatic detection stays on, any manual correction gets overwritten the next time the network changes.
To fix this permanently, you disable automatic detection and lock in the zone yourself:
Settings ➔ Additional settings ➔ Date & time ➔ turn off Set automatically ➔ Time zone ➔ select the correct zone.
Once Set automatically is off, the phone keeps the zone you chose regardless of which network it connects to. This is useful if you travel often but want your device to stay on your home time zone, or if your carrier reports the wrong region.
If you switch time zones frequently, for example on regular international trips, leaving automatic detection on is usually more convenient. Turn it back on the same way whenever you want the phone to follow the network again.