How can customers see all product images when browsing by phone? PS1.7

[F.E.A.M]

Hello

I am using Prestashop 1.7.6.5 

How can customers see all product images when browsing by phone? 

For example I add more than one image for each product, but when open the website using the mobile phone It shows only the cover image.

Please I need help, because more than 85% of my customer are using their mobile phone for browsing and ordering

This is my website http://www.learnex.bh

Thank you