Conditional format or some formula to fill in Yes when you only type y and No for n

When I have spoken to a named person for the guest list and I type y in Column E and / or Column F it should fill in Yes and No for n

Conditional format or some formula to fill in Yes when you only type y and No for n

It seems what I have done only works when the top row it says yes then it follows with yes but not for No. but when I delete all it does not work