Problem w/ background color

This s/b simple but having a heck of a time. I have text boxes that I have made the background color light yellow.

when i go to test it out, the background is gray. when i type in the field, it does turn yellow but as soon as i tab to next field, it turns back to gray.

However, this doesnt happen to radio buttons. it stays yellow like i want it to.

thanks for any help.