HOW TO MOVE OLD ZEPHYR TESTS TO NEW ZEPHYR

You could export them from one project and import them into another: Import Test Cases | Zephyr Scale Cloud Documentation (smartbear.com)

Another option that might work for you is to keep the test cases in your old project, but add them to a test cycle in your new project.  This method is how you would create a central test case repository and share those tests with other projects.

Hope that answers your question