Box 17, Code AC shows the CY amount, not the amounts for the last 3 years.

If you are looking for input fields for the last 3 years' gross receipt, those are found under General > Miscellaneous Information, on the Miscellaneous tab, under the Other Information (Schedule B) section, under the heading Business Interest Expense and Gross Receipts (-1 if not in existence).  General > Miscellaneous Information is kinda an odd place for these entries.

These entries will trigger the Y/N response for 1120-S, Sch. B, Box 10.