Google app script to subtract a cell in column 22 from a cell in column 24 in the same row on a change trigger. The script I have subtracts all rows

The following script subtracts all rows in the sheet when the on change trigger executes. I require the script to only subtract the row on which the change is made.

  var sourceSpreadsheetID = '1r4e4BNKwsmdC2Ry93Mq-N49zj3DAZVpHG21TgTe0FWY' ;
  var sourceWorksheetName = "CONCRETE";
  
  var docketSpreadsheet = SpreadsheetApp.openById(sourceSpreadsheetID);
  var docketsheet = docketSpreadsheet.getSheetByName(sourceWorksheetName);
  var maxRows = docketsheet.getMaxRows();
  var loadRange = docketsheet.getRange(2, 22, maxRows);  
//row, column, number of rows
  var totalRange = docketsheet.getRange(2, 24, maxRows);
  
  var soldValues = loadRange.getValues();
  var totalValues = totalRange.getValues();
  for (var row in soldValues) {
  var soldCellData = soldValues[row][0];
  var totalCellData = totalValues[row][0];

  if (soldCellData !== "" && totalCellData !== "" ) {
  totalValues[row][0] = totalCellData - 
  soldCellData;
  
}
}
loadRange.setValues(soldValues);
totalRange.setValues(totalValues);
}```

Thanks, your assistance is greatly appreciated