I had to get a new phone and now I can’t pair my watch with my new iPhone.

First, unpair the watch from your old iPhone using your old password. Here are two ways to unpair your watch if you no longer have the paired iPhone:

• See the 'How to erase your Apple Watch if you don't have your iPhone' section of:

Unpair and erase your Apple Watch - Apple Support

• With a web browser, go to: https://www.iCloud.com and sign in with your Apple ID. Open Find My iPhone and select All Devices (at the top). Then click your Apple Watch, select 'Erase Apple Watch', and select Next until the device is erased. Finally click "X" next to remove your Apple Watch.

Then pair the watch to your new iPhone using the new password.:

How to pair your Apple Watch with a new iPhone - Apple Support