The capablities of jD3.9 and jD4 series are generally the same but the screen views are slightly different.
It is anticipated that the majority of users, especially those who are new to jDownloads, will be using a jD4 version.
As a consequence the articles are gradually being revised: (i) to update the links; done and (ii) to use images from jD4. 
Apologies if there is any short term disruption to an article of interest.