Http hard coded into images on homepage

I have just changed hots and now my SSL is not working on my homepage due to mixed content . Both my host and i have run search and replace and other ssl plugins but it seems the images (5 images have http hard coded from them and i cannot change to https.
I nee dsomeone to help here. it seems to be a them problem. We run a very low income site from Cuba and cannot pay to fix this . Please tell me how to fix or delete this http from loading for these images

My site is https://trinidadsightseeing.com.
This is an example of the problem
(index):1 Mixed Content: The page at ‘https://trinidadsightseeing.com/’ was loaded over HTTPS, but requested an insecure image ‘http://trinidadsightseeing.com/wp-content/uploads/2016/02/cuba-cars-1224713.jpg’. This content should also be served over HTTPS.
My hosts says These resources would need to be updated in the code of the site by your web developer or designer. Unfortunately, if the plugin doesn’t correct these, they may be hard coded into the them itself. This would require someone familiar with the code of that theme to update the references to HTTPS.

Hello there,

Try to fix it with this plugin:

Flush applied site cache before reloading your site.

If it doesn’t help, you’d need to delete your slide images from Appearance > Customizer; and re-upload them.

Regards,
Kharis