從 2019 年 9 月開始，Facebook會將預算設定移到廣告帳號的行銷活動層級。

Facebook正在執行一項計畫，希望提高廣告主的預算花費效益，而這項變更只是計畫的一部分。

以下是會發生的情況：

You'll be able to set one central campaign budget for all of your ad sets, and we'll automatically and continuously distribute that budget in real time to your top-performing ad sets.

用戶將可為所有廣告組合集中設定一筆行銷活動預算，Facebook則會自動持續分配這筆預算，即時將預算撥給成效最出色的廣告組合。

After September 2019, you can still control spending at the ad set level by using ad set spend limits. If you set a minimum spend limit, Facebook will aim to spend that amount. If you set a maximum spend limit, Facebook will not exceed that amount.

9 月後，用戶依然可以利用廣告組合花費上限在廣告組合層級控制花費金額。

如果你設定花費下限，Facebook 的花費將盡可能達到該金額；如果你設定花費上限，Facebook 則不會花費超過該金額。

To understand how campaign budget optimization distributes your budget, pay attention to the total number of optimization events for your campaign and the average cost per optimization event at the campaign level, instead of each ad set.