In the VeryFitPro app connected to the watch go to the User Settings then System Settings, and you will find the option under Unit Settings.
The watch has a standby time of approx 7 days, but with every hour of sustained exercise the battery will deplete by approx 1 day.
If the activity tracking on the watch is no longer being recorded on Apple Health or Google Fit then you may need to unpair the watch from the VeryFitPro APP then re-connect it. Please also make sure you allow all permissions for the VeryFitPro APP.
The watch is only able to interface with your phone via the VeryFitPro APP, so notifications on the watch and phone will need to be dismissed separately.
To extend battery life the watch will only start tracking sustained activity after approx 90 seconds.