Hi @Steve HENDY ,
Welcome to Q&A forum!
This update is pushed by the backend and not controlled by the frontend. If other users of the same list have the new look, but you don't, you can try clearing your browser cache or using privacy mode to see if that solves the problem. As for your inability to use JSON, as far as I know, both the old look and the new one can use JSON. Can you provide more details about this? Screenshots would be even better.
Good day!
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