Sometimes you can view, but not modify, some or all of the Keyword Values on a document during indexing. This can be due to the following reason:
Keywords can be configured to appear as read-only to certain User Groups. If this is the case, keyword fields when indexing may look like the following example:
In the example above, the Applicant ID field is configured as read-only. The field is grayed out and you cannot modify the contents of the field.