If you use months as columns that doesn't work. We can't add additional measures only to totals, they will appear in the block for each month. Or, if we compare quarters, that will quarters instead.
If always we have only two quarter, we may add measures for current quarter, previous quarter and their comparison. With that we won't use months/quarters in columns.
Alternatively, we may keep months/quarters, measures like Qty change appears in each months/quarters (compare with previous period). Here we shall not use grand totals for rows.
Very short sample for the first variant looks like
