When you try to change the value of a particular campaign with a new bid value we automatically calculate the campaign's proportional value.
The proportional value is the difference between the original bid value and the updated bid value. When selected, instead of matching all category bids or keep the current ones, we automatically update all categories based on the proportional value of the campaign.
Fore example, as shown in the screenshots below, If you change your campaign bid from €1 to €1.5, the proportional increase in the bid value is 50%. Therefore, all categories under the campaign will also increase by 50%.
A €0.50 in bid value increase equals a 50% increase in proportional value.
Once selected, the proportional value is applied across all campaign categories.