An ALV layout controls visible columns, sorting, filters and totals. A useful layout preserves the identifiers needed to explain each row. Sorting changes order; filtering changes the selected population. Totals therefore need to reflect the filtered rows, and a subtotal needs a grouping column that makes its meaning visible.
Save a layout variant when another run should repeat the same presentation. The variant is tied to its report. Export only after the selection and columns are correct, because a hidden field will be missing from the spreadsheet too. These exercises separate ordered purchasing value from stock value and use explicit columns. The checker looks at the layout and resulting population, rather than requiring one particular sequence of toolbar clicks.