You can set a default setting for this, so you don't have to manually change it to 'total mg' or 'total ml' each time you add a new medication. 

To change to the desired default, go to "Settings" > "General" > "Medication Units". Toggle the switch to your preferred choice: 

You can also customize the display units of any medication in Smart Flow from the 'Edit' screen of that medication. This works on both the Flowsheets and the Anesthetic Sheets.

iPad example:

Web example: