How do i make the text circled in the header more centralised?

Text in table cells has its vertical alignment set by two things:

• The vertical alignment selection in the Control bar at top:
  
• And the cell margins, set in the same place:
  

   

But the proper way to do it is to set a Cell Style and adjust all of the cell style elements there, in the Cell Styles palette:

With a style set and applied to all "like" cells, changes are synchronized and universal.