How to change AT1 value at the time of J1IEX

Hi all,,

In our case user has entered the wrong value of HSECess (AT1) at the time of GR. And stock of material is consumed. Now when users is trying to change it at the time of posting J1IEX, using CHANGE function, all values are displaying in change mode but only AT1 is in display mode, so unable to change, can anyone guide me for the required changes and other possibilities?

Thanks,