AP invoice number in leases at pn level

Hi,

Would like to use the existing functionality in PN, which is providing ap invoice number manually at export to payable window; column name AP_INVOICE_NUM and form name =PNTXPPMT export payments to payables. We would like to use this invoice number functionality within PN instead changing to a manual number after exporting to ap. Even after providing the value over here in PNTXPPMT, system is generating its own sequence starting with PN-xxxx.

Is there any profile value which is controlling this feature? Field is enabled but functionality is not working

Thanks for your suggestions.