Images don't display after actualisation

Hello, I have changed the background images for some blocks. As long as I am logged in, I can also see the new images in the frontend. When I am logged out, the changes are unfortunately not visible.

I have already updated the pages several times, but the images are not displayed. I've tested in several browsers.

Exapmple 1 (Header for example shows old image)

Example 2

Can you help?

Many thanks in advance and best regards