Click on the Keywords button in the ribbon. 

You can change the position a keyword in the tree by drag & drop.

The green arrow means that the keyword will be placed in the group that is indicated by the arrow
A blue arrow means that the keyword will be placed at the same level as the indicated item within the group.


Use the button New Keyword to add a new keyword, Edit Keyword to modify a keyword. 

Keywords can be deleted by means of the Delete Keyword button only if they have not yet been assigned to a patient.