Weird Picture handling in pages, post, everywhere

Okay, so when I add a post, service, portfolio, etc. and add a featured image, then later change the image, the site keeps them both, using a slider. Here’s the steps.

Make a new post. Text or not doesn’t matter. Add a featured image. Save. Then remove the image and add a different one. Save. Then when you go the the blog page and you see your picture thumbnail, it will play picture 1 (even though it was removed) then picture 2 using a slideshow feature that I can seem to disable.

Please help. I’m in development mode and my team and I are trying out different images to see what works best where. But not being able to remove them is just aggravating.