My white clothes tend to turn yellow...

White clothes will do this with age, with improper laundering, or after being exposed to too much sunlight. It’s tricky to remove the yellow stain, but try adding 1/2 cup borax to each wash. Or soak smaller items in lemon juice, then hang them in the sun to dry. If it’s safe to use chlorine bleach on the fabric, mix 2 to 4 tablespoons bleach in 1 gallon water and soak for 15 to 30 minutes.