remittances

we send out the remittances through Print/email purchase orders.  The suppliers email addresses are entered correctly, and in the Payment details window the email address is entered - and the question to either print or email the remittance is also entered as email.

However, every week there are several suppiers whose remittances are not sending because the question at the bottom left of the page  has been changed to Print the Remittance, from the original entry of Email Remittance.

Why is this happening when the supplier details have never been adjusted at all.

thank you for your  help