Customer call window

Hi All,
Collections ---> Customer Calls

When i query for the customer , it comes up with the first name and last name to be yellowed. I enter them and save them. When i requery for the second time, it is the same, the first and last name yellows out again even though i had already put them.

Please help!!!! It is happening for most of the customers.

Thanks,
Srilakshmi