System calculates total qty and total amount from accnt assignment lines

You have changed quantities or amounts in the account assignment lines.
In this case, the system calculates the values of the total quantity
and total amount from the values entered.
Note
It is possible that you have entered a total quantity that is different
from the calculated total of the quantities entered in the account
assignment items. The system overwrites the total quantity with the
values it has calculated from the account assignment lines. The
behavior is the same when determining the amounts.
You can customize this message. You can also switch the message off, as
required.

Error message extract from SAP system. Copyright SAP SE.