Default Choices in Dropdowns and Listboxes
Whenever you create a dropdown field or listbox using custom values, be sure to set the default selection to the most frequently selected option. You can choose the most frequently selected option using the green check-mark button to the right of the custom values input control. The default selection will have an "X" at the far left of the display text.
[...] Learn more about setting the best default values. [...]