SRM user settings plant issue

Hi All,

I am facing very strange issue ,In SRM user settings when i try to change default plant value to another plant in the list of plants assigned in org structure  its not getting changed. I am able to change other default values like company code etc.

if i use any other test id it was working fine and only very few users are facing this issue.

We are using SRM 7.0

Please let me know if i am missing anything.