Unless you freeze your bread, it's going to go stale. The only way to keep it fresh throughout the week is to slow down the staling process, and you can easily do this by keeping your bread in the right environment. The wrong storage conditions can accelerate staling, making your bread get hard faster. Storing sandwich bread requires a different strategy than storing other types of bread.
Storing Sandwich Bread
Two processes make bread lose its freshness. The first is the crystallization of its starch molecules, which begins as soon as it finishes baking. The second is moisture evaporation caused by exposure to the air. Store your bread at room temperature because the fridge accelerates the staling process. Some store-bought breads are made with preservatives to combat this, but unless you want to experiment with your load, err on the side of caution and store your bread at room temperature. Keep the bread tightly sealed in a plastic bag. While hard-crusted breads like French loaves should be stored in paper, soft-crusted breads like sandwich bread maintain their freshness best when sealed in plastic.