The setting is in: Administration Center > Features > Projects.
Automatically calculate Other Costs from product purchase prices gives you the opportunity to adjust whether the Other Costs field in the Project window will be also calculated from bookkeeping records that are related with the project. Specifically there are calculated only selected types of bookkeeping records - added or subtracted (based on the positive or negative value of the bookkeeping record) is purchase price from the Sales invoice and Cash received type of bookkeeping records and subtracted is a purchase price from the Credit Note type of the bookkeeping record.
Click Automatically calculate Other Costs from product purchase prices to turn the setting on/off.
If the function is turned on, described bookkeeping records related to the project are calculated in the Other Costs field in the Project window. Whether there are existing relations with bookkeeping records and a project before turning this function on, even these existing bookkeeping records will be calculated in the Other Costs field.
If the function is turned on, the purchase price of bookkeeping records won't be calculated in the Other Costs field of any project.
If the function is turned on, the field that is used for automatic summarization (Actual Revenue and Other Costs) cannot be edited.
When you change the settings, be sure to click Save. For more information, go to Features.