Hi Sangeetha,
In order to use this you will have to use a snippet.
- Right click in the project explorer and create a snippet
- Create an entity where the text you want the admin to change is saved.
- Create one page where the admin can change this text.
- In the snippet you retrieve the entity where the text is saved and show this as a text.
- Replace all the places where you are currently using the text with the snippet.
Hope this helps!