How to change log off time in steady state ?

Hello All,

i'm using Windows Steady State for security purpose. when we create new user in steady state the first time it will ask the user log off time .this option is already mark but if we don't need to log off our user in specific timing we need to unmark this option , but i have forgot to unmark this option.
and now when i idle for 20-30 min. my system is automatically log off . now i need to change this settings so, what should i do ?


Thanks in advance......