There are many scenarios where a certain script needs to be run before every request in the API test. For example, you may want every step to check if an auth token has expired and, if so, obtain a new one. This logic can now be configured in a pre-request script at the flow level.
To get started, use the pencil icon in the flow title card to bring up the flow properties modal.
In the modal head over to Pre-request tab and edit your script code as needed. Close the modal using the X icon when you are happy with the script.
For more information on how you can add custom scripts to your API tests, check out the guide.