OnePlus: Set Time Zone and Region Manually

Your OnePlus phone keeps resetting to the wrong time after you switch regions because Use network-provided time zone stays enabled by default. This setting pulls the time zone straight from your mobile carrier, so any manual change gets overwritten the moment the phone reconnects to the network.

Turning that function off is the first step. Open Settings ➔ System ➔ Date & time ➔ Disable Use network-provided time zone. Once automatic detection is off, tap Time zone ➔ Region (country/region) ➔ Select a country or enter a name ➔ Choose a suggestion ➔ Choose a time zone to lock in the correct zone.

This setup matters if you travel often or use a SIM from another country while keeping local settings. Leaving network time enabled works fine at home, since it updates automatically for daylight saving changes. Once you switch to manual mode, you are responsible for updating the time zone yourself if you move to a different region again.