2nd Local Currency in OB22 Not Changable

Dear Experts,

I need to change the 2nd Local Currency in OB22 which is coming in display mode unfortunately whereas all other fields are editable for 2nd local currency (screenshot for your reference).

As of now only one document is posted in this Co. Code in Client 810. And the field of currency in 2nd local currency is non editable in Client 800.

Kindly suggest how to resolve.

Thanks in Advance