timestamp default current_timestamp not working

I am not getting the timestamp value which i am expecting to be automatically inserted in the column defined: 

...

"timestamp" timestamp with time zone DEFAULT CURRENT_TIMESTAMP,

...

(I see the above definition in pgadmin4 in the tab SQL. 

I have set it thru pgadmin4 table->properties->columns by entering CURRENT_TIMESTAMP in the default column)

why is the timestamp value not being automatically inserted by the system