SSL problems – images

Hi, I am not able to change the adress of my images from http into https. I uploaded the images again, but it's still http. I tried changing a few images (in the featured images section on homepage) manually into https. It worked, it was changed, only now my website is not safe anymore. In the logo section I cannot change manually the url, but I'm affraid I broke the 'SLL' safety by changing it manually. When I'm logged in, I now see the red triangle: NOT SAFE! So my question is: - do I need to manually change the URLS of the images? - Or should i upload the images again so they will automatically be https: ? Why are they not automatically changed into https ? This way doesnt work... http://www.bijbambini.nl