How to active Org unit field on IT0001

Dear all,

My problem is one Position assign for multi Organization Unit and when I input data on PA30 system allway default the first organization unit on Org Unit field (OREGH) IT 0001.

I want to active Org Unit field (OREGH) IT 0001 to key in on this field by manually. I don't want to deactive OM-PA relationship because I want to get cost center automaticly.

Please help me to solve this problem.

Many thanks,

H.N