HI naveen ,
I am not sure but can you check the below :
Go to SPRO path :Define Customer Table Extensions on Header Level
In this Customizing activity, you define header level table extensions for all supported business objects. To do so, you define appends in data dictionary structures containing the fields you want to display on the user interface and/or write to the database.
STeps :
1. Define an append containing all the database fields included in the header extension tables. If no append exists, the system automatically creates one with the naming convention ZA<structure name>#, where <structure name> is the name of the structure to which the append is assigned. If you want to create the append with a different name, cancel processing, confirm that you do not want to save changes, choose Appends and a different name on the popup. If there are already existing appends, you can choose one from the list or create a new one.
2. Add the required database fields to the append. If you need the same list of fields in different appends, you should create a structure by means of transaction ABAP Dictionary (SE11) and include it wherever required by creating an entry #.INCLUDE# for the field name and the created structure.
3. In the follow-on activities, you can create or change appends with the fields of the business object-dependent extension tables. The processing is similar to the first activity, but these structures are used for displaying extension tables on the user interface.
then go to Configure Control of Fields of Table Extensions >>Customer metadata for substructure fields in normal entries and set the action there
You may also explore this one : Configure Control of User Interface for Extension Tables
In this Customizing activity, you can influence the behavior of the generic table extension display function on the user interface. Since the customer namespaces #THCUS# and #TICUS# are used, you are allowed to make settings for customer table extensions only.