Watch keeps ringing after phone answers call

Hi

If you have not yet done so, it may help to update your iPhone and Apple Watch to the latest software, starting with your iPhone (note that iOS 10 and watchOS 3 are due to be released later today):

• Update the iOS software on your iPhone, iPad, or iPod touch - Apple Support
• Update the software on your Apple Watch - Apple Support

The following further steps may also help:

Restart both your iPhone and your watch:

• Turn both devices off together, then restart your iPhone first;
• Restart your iPhone, iPad, or iPod touch - Apple Support
• Restart your Apple Watch - Apple Support

Unpair and re-pair your watch:

• The Watch app on your iPhone takes a backup of your watch automatically when unpairing via the app. Choose to Restore from Backup during set up. Most data and settings will be restored, with some exceptions (eg Apple Pay cards, passcode).
• Unpair your Apple Watch and iPhone - Apple Support
• Set up your Apple Watch - Apple Support