Only In Progress JVs can be modified.
Navigate to FGAJVCQ and enter the JV number in the Document Number field.
Tip: If the JV number is unknown, look it up on FGIJVCD.
Click Go (or press Alt+Page Down) to move to the Document Header.
Click the Next Section icon (or press Alt+Page Down) to move to the Transaction Detail block.
Use the left and right keys (Next/Previous Record icons) to view the records in the JV.
Make desired changes.
Complete the JV according to the instructions in Complete a JV.