I need help with cleaning copper food molds, please...

Try this method on u tube.how to clean copper utensils(without using your hands,copper utensils are clean and shinning) - YouTube

You can use plain white toothpaste to clean copper.

I would use a dish soap like Dawn to cut the grease and clean well. Then I would use the product Tarnex on cotton balls and wipe the metal to remove tarnish. After the metal is all shiney again I would rinse the mold very well and dry with a soft cloth immediately after. I would NEVER spray the molds with ANY type of paint or clear varnish, especially if you ever plan to use them to mold gelatins or cakes etc.

I have heard ketchup and baking soda mix - used it a couple of times and was surprised at good results.

Here's a tutorial that might help - https://chascrazycreations.com/copper-cleaning-hacks/