Editing your own foods
Foods you created are fully yours: open one and tap Edit, and the same two-step editor opens with everything changeable — name, serving, nutrition. (Swiping a row in My Foods deletes it rather than opening the editor.) Entries already in your diary keep the values they were logged with, so fixing a food today doesn't silently rewrite last month.
"Editing" a catalog food
Foods from the shared catalog can't be modified in place — thousands of people log the same entry, so one person's correction can't overwrite everyone's data. Instead, scan the product's barcode and choose Edit values on the food that comes up: you get your own editable copy, prefilled with the original's data, marked clearly as yours. The offer belongs to the barcode flow — it isn't on a catalog food you reached from search.
Your copy is what you'll log from then on — it shows up in My Foods and in your search results alongside everything else. The catalog original stays untouched for everyone else.
When is this worth doing? A label that changed since the catalog entry was made, a regional formulation with different macros, or a product whose serving size you want defined your way.
Duplicating
Your recipes can be duplicated from their detail view — handy for creating variants (a base with one tweak) without rebuilding the ingredient list. Custom foods don't duplicate; for a variant, edit your copy or create a second food.
One rule to remember
If the food's numbers came from you, you edit it directly. If they came from the catalog, you edit your copy of it. Either way, nothing you do reaches other users — unless you explicitly contribute a food to the catalog.