Sheet print configuration changes after printing

Hello to all, I am using DS 2026 sp1 and I am facing the following problem.  

I have setup my sheets properly, with the desired print configuration.  Every time that I print some (not all) sheets the print configuration changes to default.  To revert it I have to open the "Print Configuration Manager..." and then close it immediately without changing anything.  Then the print configuration is fixed.

This is very annoying.  Is there anything I can do about this?  Or, am I missing something here?

Thanks in advance

Vassilis