Change image in gallery?

Question

WordPress

Prompt a plug-in of the following character.
In the GALLERY widget (standard wordpress) I created a gallery of several images

(((примечание...при клике на какое-то изобр. перехожу на запись-при помощи плагина-это уже реализовано)

How to implement so that not all pictures of the gallery are shown in the GALLERY, but only one (or two or three - but not all) - and when updating / reloading the page, others are shown ((one or two or three - but not all))) pictures of the same galleries.

Answer 1

The code

Answer 2

It seems to me that it's faster to write code with your hands (there are several lines) than to look for a plugin.