On the user chat window, long press on the sent or received chat message.
A message selection-copy window is opened, as shown below.
Select the check boxes of the messages, which have to be copied.
Click as directed by the arrow as shown in the below figure.
You will be taken to the collapsible pop-up menu as shown in the below figure
Select as directed by the arrow from the below figure.
The selected messages are copied.
Note: To paste the copied messages:
Click on the chat type area and see the paste Icon.
Click , as directed by the arrow from the figure below.