As you build a recipe you see a list of ingredients on the screen. Although these ingredients will have ingredient declarations set into them from when the ingredients were created you may choose to adjust the declarations that apply for this product only.
To access the ingredient declaration fields within the recipe use the drop down arrow to make the extra fields visible.
Any changes you make to the ingredient declarations here will be reflected in the labels / reports for this product but it will not affect the original ingredients.
Be aware, if the ingredient was set to simple type when it was set up then any text you add to the short and long declaration field will not show up if added via the recipe.
If you find you did want adjust a simple type ingredient at the recipe stage just go back to the ingredients and set it as compound. It won't matter if only the Declaration field has text and the long and short declarations are blank but it will mean they can have text included once the ingredient is in the recipe.