Xiaomi
Set Date Manually auf Xiaomi
Xiaomi phones running MIUI fetch the current date automatically from your mobile network by default. This keeps the date accurate while traveling or switching SIM cards, but it also blocks any manual change you try to make.
If you type in a different date and it snaps back to the network value, the automatic sync is still active in the background. You need to switch it off before the phone accepts a manual entry.
To change it, go to Tap on Settings ➔ Tap on Additional settings ➔ Tap on Date & time ➔ Disable Use network-provided time ➔ Tap on Date ➔ Set the Date and tap OK.
Once network-provided time is disabled, the date field stays editable and keeps whatever value you set, even after a restart. Keep in mind that some apps rely on an accurate system date for security checks, certificates, or scheduled reminders, so only disable the sync if you have a specific reason to set a custom date.
If only the time zone is wrong while the date itself is correct, check the time zone setting in the same menu instead of disabling network time completely.