Kmail changes destination folder sends to wrong folder

I’ve set up several inbox folders for different email accounts. In the POP3 advanced dialog, there is a space for destination folder which I specify. This works most of the time. However, occasionally, it changes spontaneously and my emails for various accounts go to a folder for a little used account I have. This little used folder actually shows up in the destination folder dialog for the changed accounts. I go in and change the destination back and everything works fine for a while - hours, days it seems random - when the problem happens again.

Two questions:

How do I make it stop?

If it won’t stop, is there a way to change what seems to be what Kmail (or akonadi (I’m making a wild guess that this is an akonadi problem) considers the default folder?