Changing default app to open files - keeps reverting ?!?

[fx600]

Hi, running Leo 10.5.1, vanilla kernel EFI v8.

 

I have got this strange problem - every time I try to change default application for opening specific file type (e.g. Excel, PDF,...), it reverts back to the previous application.

 

That is, in the Info window I change the application to another, then press Change All, it asks me if I want to open all similar files in the new application, I do OK, but it immediately reverts to the old application...

 

I tried repairing permissions, but that didn't help...

 

I am at a complete loss what do do with it?

 

Thanks for help.