How to change Bibliographic style in EndNote Web

I am writing an article for the Journal of Parasitology.

I have selected J Parasitology from the Style: drop-down menu in Word, which formats the bibliography. 

However, the editor has told me that the colon following the volume number should be in bold font. See attachment.

How do I change the style so that all these colons are in bold?

Perhaps this just isn’t possible … ?

I’m afraid I’m struggling to find the ‘Edit’ button you mention - can you see it in my screenshot above?

I also can’t see how I would change to a style that’s not already in the Style: drop-down list.