To change the time on a Fitbit, you'll need to adjust the time zone setting for your device on the Fitbit mobile app or desktop website.
You can sync your Fitbit with an iPhone through the mobile Fitbit app. There are also a few tricks you can try if your Fitbit ...
Restart > clean connections > use a different charger > replace the cable > bring the phone closer. Check Bluetooth connection > disconnect other Bluetooth devices > restart Fitbit app > check for ...