The advanced assembly settings can be found the under the "More options" button. To access the advanced assembly settings, select "Custom Sensitivity" from the dropdown box next to "Sensitivity". The advanced options will now be available.
Before doing this it is a good idea to select a standard sensitivity option which fills in appropriate default values for the advanced options, i.e. if you select "Low Sensitivity" then select "Custom Sensitivity" the advanced settings are pre-filled with the settings used for low sensitivity.