Step 1 : Navigate to "settings" > Company > Advance settings > Custom fields > Click on "Add"
Step 2 : Update the following information > click on "Create"
a. Select the Entity type as "Containers"
b. Enter the Custom field name.
c. Set Priority: This allows the user to determine the placement of the field within the container, specifying where it will be displayed.
d. Select the "Type" of the custom field : Text, List of values, Boolean or date.
e. Default Value : Set a default value of the custom field, if required.
d. Check if the field needs to be mandatory.
You have successfully created a custom field for a container. You can see the custom field now on Container Configuration
Simply navigate to : Stock > Container > Click on the container > Configuration