Previous price
You can click Previous Price in the Price Change Details window to view the price that was in-effect before the price/date you selected in the Advanced Price Lookup table. For example, you are viewing the price for a widget on 2/2/19. You can click Previous Price to view what the in-effect price was for that widget before that price on 2/2/19.
When you click Previous Price, the table is re-displayed with a Starting Date of one day before the in-effect price for the price/date you selected. The previous in-effect price for the item is then loaded into the table. The Ending Date is the same date as the in-effect Starting Date for the price/date you selected.
For example, the in-effect price at the price/date you selected for a widget has a Starting Date of 4/2/19 and a price of $50.00. You click Previous Price to load the price that was in-effect before the date/price you selected. The Advanced Price Lookup table is re-displayed with a Starting Date of 4/1/19, an Ending Date of 4/2/19, and a price of $60.00.
If a given price/date/location intersection in the Advanced Price Lookup table has multiple prices associated with it, each price change displays its own button.