Implementing bid factors on the exchange level in DV360 is very simple!
This can be done by adjusting the Bid Ratio (%) on the Inventory Source level.
1. Within your Campaign, click into My Inventory where all of your inventory sources will be listed.
2. Scroll to the right to find the Bid ratio (%) option under Delivery. Adjust top performing exchanges percentages accordingly.
Another option is to adjust budgets on the line item level, however note that this will affect all of the inventory sources being targeted, which may contain multiple exchanges. Just make sure that your settings are set to Control bid and budget at the line item level in order to make these manual adjustments.