Set the value of a form from the controller

I have categories which have many products and a form which displays drop-down menus of both. Once a Category gets picked the values of the Product drop-down get filtered so that only products which belong to the category get displayed. That works fine until the user sets the selectedProduct drop-down to a specific value.

How can I reset the selectedProduct drop-down to All Products if the user clicks on a different Category after he clicked on a Product?

app/templates/index.hbs

{{view "select" prompt="All Categories"
                content=filteredCategories
                optionLabelPath="content.name"
                optionValuePath="content.name"
                value=selectedCategory}}

{{view "select" prompt="All Products"
                content=filteredProducts
                optionLabelPath="content.name"
                optionValuePath="content.name"
                value=selectedProduct}}