Why is my nail polish turning my nails yelow?

It shouldn't, nor should nail polish remover. Typical things that turn nails yellow are exposure to tobacco and smoking, exposure to the spice, turmeric and fungal infections. If your toenails are yellow too, think more in terms of a possible infection. - Use a base coat or top coat before you apply the color polish to your nails and then when you remove it your nails shouldn't be yellow!