Add a new value to an existing picklist
Note: Before you start, you must have the Pick List [R/W] role to perform these steps.
You may create a new picklist value from within the picklist field on the item it's used in.
On the far-right side of the picklist drop-down field, click Create.
In the Quick Create dialog, enter a new value in the Value 1 field.
Ensure the Show all fields is toggled on and enter the List Name the new picklist value should be included in.
Click Save & Close.