How can I log in to my new Apple Account on Apple Watch?

Indybuck84 wrote: The old Apple account was used on my iPhone but was tied to a prior work but after leaving I changed the account.

I somehow suspect your changing your account on the iPhone from the old work one was not as thorough as you suspected. To do it properly you need to completely reset a device between accounts. If you do not, ghosts of the old account and its files can hang around the device and mess with things. What to do before you sell, give away, or trade in your iPhone or iPad - Apple Support While a device is designed to be used with a single Apple Account, it is possible to use others for specific purposes and maybe one of those is still resident on the iPhone?

There are several likely places where you can use a different Apple ID:

1. In Mail if you want to use a different, or more than one, iCloud or other mail provider account, go to: Settings -> mail -> accounts -> add account -> iCloud

2. Messages and Facetime. Sign into a different Apple ID for these services in Settings. Note this has to be the same ID for both. Go to Settings > Messages > Send & Receive, and make sure both your telephone number and Apple ID are input there and both show a checkmark. If you need more help, check this link: Add or remove your phone number in Messages or FaceTime - Apple Support .

3. In the support article: If you subscribe to Apple One and use a different Apple ID for iCloud - Apple Support Apple alludes to using a different Apple ID just for media, subscriptions, and purchases, but doesn't describe how to do this. See if these work:

In iOS/iPadOS: Go to Settings > [your Apple ID] > Media & Purchases. Sign out of the current ID and sign in with a different one.

In Ventura or later: First, quit Settings. Then, in App Store, choose “Sign Out” in the Store menu, then click on the “sign in” button that appears in the main window. You can then sign into the other account. (from: https://discussions.apple.com/thread/254568066 )

Related to that is: Use a different Apple ID to share purchases with Family Sharing as outlined in Use a different Apple Account to share purchases with Family Sharing - Apple Support

You probably have an app on your phone, which is trying to install on your watch, that was purchased with the old account.

Delete the app and re-download it using your current apple account.

The only way of which I know of doing this is to manually update Apps one by one and see which ones complain.

How to manually update apps from the App Store - Apple Support

Unfortunately when you changed devices you didn't simply change the email address used on your account. By setting up a new account you won't have access to things done with the old one unless it is not too late and you decide to revert to the old account. Let us know what you want to do and we can help.