How to calibrate the time of the Xiaomi Smart Watch and the Xiaomi Smart Band?

The device's time will be automatically calibrated with the phone's time when connected to the phone. If the device is shut down due to power failure, after recharging, the device's time will be displayed as the time before the device was powered off. After restarting, the device should be connected to the mobile phone for time calibration to restore the correct time.
Note:
The time format of the device is consistent with the time format of the mobile phone (24-hour/12-hour format).