Custom variables are fields that can be used to automatically populate custom user information when a Form is being filled out by a User (eg: License number or vehicle number, etc). Adding the variables that you would like to use is a simple process.
To begin, go to the Users list via the web portal by going to Users > View Users. Then click on one of the arrows on the right end of the user rows to open up the information and permissions card for the User.
Once on that page, you can scroll to the bottom of the permissions list, and you will see there a section titled Form Variables.
To add a new variable to the list, you can click on the + Add Variable button, and a new line will appear, which you can title in the left hand field. Press Save after you have titled the line, and the new variable will now also show up when you go to edit other Users as well.