how can i set uo my preowned series 7 apple watch that the previous owner didn't sign out on

The person that you bought/got this watch from needs to follow all the steps on this page;

Remove the Activation Lock so that the buyer can use it.

If they can't or won't then get your money back or recycle the watch and mark it down as a bad experience.

Neither the users on this forum or Apple can help you,only the original owner can help you.

No one has that information.

Apple values your privacy and has safeguards in place to ensure that no one can access the device.

You will need to reach out to the owner because it is the owner’s responsibility to properly erase the device before selling it.

Until then, it is locked. 🔐