Use this option to edit the keywords in the database. You may select one or more keywords in the list at the left, then click on the buttons on the right to operate on them.
Delete. Removes the keywords from the database. This also disassociates any thumbnails from the keyword.
Change. You can type a new value for the keyword. It will remain associated with all thumbnails that were associated with the original. This button is only available if a single keyword is selected.
Combine. You may combine multiple keywords to a single database entry. Extra associations (i.e., references to more than one of the selected entries) will be dropped. This button is only available if multiple keywords are selected.