Moving targets in the KMail folder list

Hello,

I just started using KMail 5.7.3.
I have a folder list at left. There are several folders that contain mail 
folders. E.g. the folder KDE has subfolders KDE-PIM, KDE bugs and KDE forums.
But these last ones change position all the time. Same for e.g. the trash 
folder. Sometimes it is high up in the list and then it jumps down to 
somewhere below.

It is very difficult to hit a folder by habit if they are moving all the time 
and you have to search for them in the list.

I did a lot of searching through the Settings, but could not find a "freeze 
then where they belong" setting.

Anybody?

-- 
Regards,
Henk van Velden