If I forgot to erase my phone from old phone and now I cannot connect with new phone what to do? I did try to restart it, it doesn't work

I had to switch my phone but my watch stayed series 8. I cannot connect my Apple Watch to my new phone. Tried all different ways it keep asking for my password and I keep putting in but still nothing, and my location on my watch is showing different that is my current location . that's a little strange what to do?