Xiaomi
Change the Time Zone Manually auf Xiaomi
MIUI reads the time zone from the connected carrier network by default. This is convenient while traveling, since the clock adjusts automatically, but it also means the time zone changes without warning whenever you switch networks or use a local SIM abroad.
To set a fixed time zone yourself, you first have to turn off the automatic detection. Open Settings ➔ Additional settings ➔ Date & time, then disable Use network-provided time zone.
With that option off, tap Select time zone ➔ Region, choose the region, and then pick the exact time zone from the list. The phone keeps this setting even if you connect to a different network afterward.
Leave the network-provided option enabled if you travel often and want the clock to adjust automatically at each destination. Turn it off only when you need the displayed time to stay fixed, for example when scheduling calls with a team in another region.