Find & Replace

It's a problem reported a few times here, and I suspect interference from other software. Usually in another (virgin) account, all works well.

You can try to find if any of your login items, menu add-ons, or custom keyboard shortcuts are responsible by disabling them one by one (or many together) and logging out/in between each experiment.

If you find that you'll be a hero to many.

I suggest quit Numbers and restart Numbers.

after that log out then back in. after that restart the machine

maybe Numbers is not the active application? I cannot tell from the screenshot you provided. What does it say in the top left corner of your screen?

Please post a screenshot with more context.