Max bid thresholds can only be set at the campaign level. However, to apply a common max bid across multiple campaigns, follow these steps:
Go to the Campaign Manager page.
Select all enabled campaigns you want to update.
Click on the Actions menu and choose Update Threshold.
Select Max Bid Threshold from the dropdown.
Enter your desired max bid value and hit Save Changes.
This approach allows you to quickly set a uniform max bid across selected campaigns, ensuring consistent bidding limits without having to adjust each campaign individually.