Hey minda0244,
Congratulations on your new Apple Watch Series 7!
It appears that you're having a problem setting up your new Apple Watch. When it asked you to sign into FaceTime, you had to reset your Apple ID password since it showed you your old Apple ID. The problem is, you can’t get past this and complete the set-up process, and we're glad to provide assistance.
Use FaceTime with your iPhone, iPad, or iPod touch - Apple Support -- On your iPhone, go to Settings > FaceTime, and check which Apple ID you're using on your iPhone. If it's your old Apple ID and you just changed its password, scroll down to "Caller ID”. Then tap "Apple ID", select Sign Out. Then sign back in again with the new password. See if you can complete setting up your new Apple Watch now.
Unpair and erase your Apple Watch - Apple Support -- If you still can't get past signing into FaceTime on your Apple Watch, scroll down to "How to erase your Apple Watch if you don't have your iPhone" in this article. Erase All Content and Settings, which will place you back at the start of setting up. See if you're able to complete once again.
Let us know how that goes.
All the best.