Before posting, approving, and/or paying an invoice, we can edit the distribution on the GL Distribution tab. Sometimes after entering the GL Distribution, the Invoice amount needs to be increased or decreased. If GL Distribution has already been entered, it will update the existing line items' totals to reflect the new amount. Those lines may have been correct and new lines of distribution were needed so the existing lines to be re-entered/edited for the correct amounts.
Edit the distribution on the GL Distribution tab to the desired amounts. Then select the Invoice tab and update the total amount. This will keep your GL Distribution correct and avoid re-entry/loss of data.