Open a day on the Meals tab, swipe right on a food and choose Made It for a recipe or Had It for a pantry item. Made It asks how many servings you made. Not Made and Not Had put it back. On Home, the next meal’s card has a Made It (or Had It) button too.
With When I Confirm, a note on the meal plan, such as “3 past meals to confirm”, asks about past meals you haven’t confirmed. Tap Confirm All, or Review to uncheck the ones you didn’t have: unchecked meals are left alone, and you won’t be asked about them again. The ✕ on the note puts the question off until tomorrow.
The note asks about every profile’s meals; when they belong to more than one profile, Review shows whose each one is. Meals more than two weeks old aren’t asked about.
Choose how long it waits before asking — After 1 day, After 2 days (the starting choice), After a week or Never — in Settings → Keeping Count → Ask About Past Meals. It’s there while Planned Meals Leave the Pantry is set to When I Confirm, and it’s set separately on each device.
Had It is offered for pantry items counted Automatic. None of these show when Keep Count of What I Have is off.